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  1. 75gmck25

    8 Lug Dually wheels

    Not sure what pattern the Ford Transit wheels are (same as F250?), but its unlikely to fit. Older 8 lug wheels often had the same pattern for multiple manufacturers and they were lug centric. If the hole in the middle was large enough to fit over the hub, they worked. Many newer 8 bolt Ford...
  2. 75gmck25

    Mysterious wires/plugs in engine compartment

    Does the truck have a auxiliary battery tray on the drivers side? With a 2nd battery it would have a relay on the driver’s side fender well to control the charging. It isolates the 2nd battery when the ignition is off, and the middle plug looks like the right type for the original relay.
  3. 75gmck25

    Opinion on cylinder heads

    Do not waste your money buying stock SBC heads from the smog era. They are low compression, low flow components that are like putting a restrictor in the middle of your engine’s airflow. Save up your money and buy Vortec equivalent heads, or one of the many aftermarket aluminum heads. You...
  4. 75gmck25

    Power only comes on intermittently

    Your truck is much newer than mine, but in my truck it would be the fusible link that comes straight down from the power junction next to the brake booster. This 10 gauge wire with 14 gauge fusible link is what powers the dash and the HEI. If it has too much current it will start to burn...
  5. 75gmck25

    Broken hearted kid and fuel system

    First - I want to make sure this is how it’s plumbed - you have the fuel inlet hose from the tank connected to the 3/8” Barb/push-on fitting and it has a clamp. It should be a short hose that runs over to a 3/8” line on the frame rail, with a clamp on that end. - small barbed fitting should...
  6. 75gmck25

    Ammeter Fuse size?

    IMHO, a big block swap is usually not worth the trouble unless you have the money to build it correctly. Swapping in a relatively stock BB gives you bragging rights, but it’s primarily going to give you good torque for towing or hauling. Getting high HP out of a big block will cost money.
  7. 75gmck25

    NP 203 Shift pattern

    If you have an unconverted NP203. In the Hi or Lo positions you have all wheel drive ( AWD) or full-time 4WD. Great for winter or muddy driving. There is a differential in the transfer case that lets the front and rear axles turn at different speeds, so you can also drive on hard pavement...
  8. 75gmck25

    Are front wheel bearings adjustable?

    IIRC, after repacking them you tighten to about 50 foot lbs while slowly rotating the wheel (would have to look up the exact spec) to seat them. Then back off the nut and retighten by hand until the castellated nut lines up and you can insert the cotter pin.
  9. 75gmck25

    Center dash speaker options?

    For double din you usually have a mounting sleeve that bolts into the cutout in the dash. Then you slide a double din head unit into it like it’s the drawer in a file cabinet, and it locks in place. There are adapters to fit a single sized head unit into a double din opening. Make sure you...
  10. 75gmck25

    TH350 To a 700r4 transmission

    TH-350 is usually very reliable, and even more so if a rebuilder uses the right parts. However, with the low 4.10 gears in my truck I really miss having an overdrive. Stock height (about 31”) tires help a little, but it still turns a lot of rpm on the highway.
  11. 75gmck25

    Ammeter Fuse size?

    I replaced the ammeter fuses in my ‘75 and the ammeter still didn’t give any decent reading. I then did the conversion to a voltmeter and moved on. The only glitch is that the new voltmeter has much brighter orange on the needle than the old worn gauges. Using a shunt based ammeter is common...
  12. 75gmck25

    Fusible link replacement

    That looks like the same main power wire as my ‘75, which is a 10 gauge wire with a 14 gauge fusible link. These are so common that they are often marked in the Dorman product line as a “GM fusible link”. If you burn through that link the entire truck goes dead because it feeds the dash and...
  13. 75gmck25

    Drive shaft replacement

    When I lived in San Antonio there was a local driveshaft shop, and I just has them rebuild my front driveshaft. That one lasted about 18 years before one of the u-joints rusted out and fell apart. Replaced all the joints a few years ago and it’s still working fine.
  14. 75gmck25

    Drive shaft replacement

    I’d probably use the bottom one, and install all new sealed u-joints. Use sealed u-joints because everybody forgets to lube the type with zerks on them. Then lube the slip joint and make sure it slides in and out smoothly.
  15. 75gmck25

    Where can I get an OEM thermostat for a 1974 Chevy C10 with a 454?

    In general, engines have better combustion efficiency and gas mileage when they are running hotter, up to a point. You give up some power and gas mileage if it’s too cool. Most modern cooling systems seem to be designed to run in in the range of 210-230 degrees, but older systems like our...
  16. 75gmck25

    $40 well spent on OEM buzzer

    I have a universal buzzer I bought at a parts store, and used it in my ‘75. It has two leads you plug in at the fuse panel. It’s tone is fairly wimpy, but it works. You just need to find one fuse that only has power when the ignition is on, and a 2nd fuse that is powered by the headlight...
  17. 75gmck25

    Where can I get an OEM thermostat for a 1974 Chevy C10 with a 454?

    195 works better overall for a street vehicle, and can possibly help gas mileage and driveability. Using a 180 might get you a few more minutes before it hits 210, but has no capability to reduce the max temp. At 210 degrees both a 180 and a 195 are wide open.
  18. 75gmck25

    Q jet choke question

    I bought an electric choke conversion for my hot air choke Quadrajet. Seems like there should be a similar kit for your divorced choke Quadrajet.
  19. 75gmck25

    Bad Master Cylinder?

    The proportioning valve balances front and rear brakes. If front or rear brakes has a big leak, the prop valve will flip the other direction from the leak (and turn the brake warning light on) and it might stick there. You should make sure the valve is centered so it’s sending fluid to the...
  20. 75gmck25

    Ac/heat high speed fan not working

    Does your truck have a separate 30 amp fuse for the high speed on the blower? On the older trucks it’s very easy to see because the power wire, with fuse holder, runs along the top of the firewall in the engine compartment. It runs from the power junction next to the brake booster, over to the...
  21. 75gmck25

    New one wire alternator/voltmeter gauge question

    I don’t know who you have been talking to before, but they are all very confused. The dash gauge just measures voltage, not amperage. You need to use a larger gauge charge wire with the new alternator, but the stock voltmeter gauge will work fine. With a 140 amp alternator I would want to...
  22. 75gmck25

    SBC Cylinder Head Decision

    Also consider an option to get your compression up a little. The old 350 SBC only had about 8.2-8.5 compression ratio with 72 cc chambers, and I assume your new heads have 64cc chambers. You can use thinner head gaskets and it wil gets you a little more compression, but still run on regular...
  23. 75gmck25

    Automatic door lock kit

    I’ve had the kit from LMC truck for years, and it still works. However, the lock solenoids that come with it have failed and I replaced them. The new solenoids are just as cheaply made as the ones in the kit, but they are still working. Unless the prices have gone up, the universal...
  24. 75gmck25

    Preferred Solder for Automotive Wiring

    You want to buy solder that is designed for electrical work, not plumbing solder. Also remember that one down-side of solder vs crimp connectors is that solder by itself does not provide any pulling strength. If you accidentally snag a wire there is only solder holding it together - no...
  25. 75gmck25

    1977 K20 Drain Transfer case Plug

    My 203 is still full time (factory original) so I just check the oil periodically (I used synthetic 10w30). Only the 203 cases that have been converted to part time need to be put in hi-loc every month or so to fully lubricate them.

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