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Any Dex/Merc certified fluid will do. Dex VI is said to be backwards compatible but not necessary.
OK, that was it then. I was 2nd guessing. I have 2 or 3 early cores. I'll probably pull the valve bodies and trash them. If and when I do build them anymore, it's an 87 or later. Haven't built one now in about 20 years.
Like Nick said, Dex 3 or later. I run the blue bottle Valvoline Dex/Merc fluid from walmart in my TH400's and 4L80 that call for Dex III. It's $18/gallon. I run the red bottle Valvoline Maxlife or ACDelco Dex 6 in my 6L80 that calls for Dex 6. You can get it for $24/gallon at walmart. The synthetic Dex VI is better with heat, so if you aren't going to run a BIG external cooler with your 700R4, I'd spring for the extra $5/Gallon and use the Maxlife.
Don't trash those early cores, simply converter them to the L84-87 standard via swapping in a '152' input drum (30 spline) and 303/304 pump cover and body assembly (non-aux valve body style pump). Install the updated 29-element input sprag gear assembly, 4L60E forward wave/cushion plate, coast clutch backing plate and 4L60E 3-4 steel module and you'll be good to go. 700R4s are getting very hard to find so even those early 82-84 27-spline units are fetching over $300 as rebuildables here in Vegas.
I think we all need more reasons to keep old junk around, especially when talking about complex assemblies like driveline or even certain suspension/steering parts. The future is not going to be kind to l e g a c y technology and will try to tax or regulate it out of existence
I've got $hit laying around I'll never use. I know it's good to someone. Some of it I do want out of my way. My main deal is, I want in the hands of someone who'll use it or needs it. I can't see scrapping it. Like these older 700r4 cores. I've known for sometime I'd never build them for anyone or sell them, but I knew the valve bodies in them were good, and I was hoping maybe they'd been rebuilt before and I might open then up and find Beast Sun Shells in them since just about every rebuild gets at the bare minimum a Beast Sun Shell. However, now days, there's the Smart shell which is by far better and worth it all day long, but there is also China made SAID TO BE the BEAST sunshells and they are NOT. Buy yeah, guess I'll keep them around for case cores. One of my 93 cores does have a broken bell housing. So see, what Nick is saying, and I knew many parts are backwards compatible, so I can likley use those hard parts and make one of these older cases good, especially for someone wanting to do a #'s matching restoration project. Some people are picky that way. They want the right #'s on the case, or many 60's build guys want the right tag on the Th400 or Th350 case.
Go to Pick-a-Parts and start looking at GM Squarbody trucks in the yard, particularly at the trans cross members and relationship to the frames. Maybe take one that looks 'correct' loose to see how it would sit/set up prior to being bolted back in place. What you're trying to determine is if your x-member is correct, whether the x-member is tweaked/warped and/or whether your frame rails are tweaked/warped.
Can you unbolt the mount from the frame put it in the way it needs to go and redrill the frame. You have have to add a piece to the cross memberto make the mount pad stick out far enough to hit the mount. A piece of 3/16 plate and a little common sense should get it done.
I'd say it did come with a 700r4. That was the most common transmission by 84 and your 4YPOOB, the 4 would designate an 84 model so it's likely the OEM transmission. Even if it were a Th350, I'm 95% certain, either transmission would use the same crossmember, they just might use a different set of frame punched bolt holes. One will set the crossmember a bit futher back than the other.
I'm slow, it took me a minute to figure what the **** was in your post. I was going to correct it and use a 0 in **** but then realized, if you take the space out that doesn't belong, we can say cockeyed.
Transmission mount is ~3/4" further back on a 700R4 than it is on a TH350. Both TH350 and 700R4 were available in 84, and it was the last year for the TH350. You could look at your SPID sheet to see what one your truck came with from the factory. MD8 or MX0 is the RPO for a 700R4. MX1/M38/M49 are the RPO's for a TH350. M40 is the RPO for a TH400
