Help - Inherited a 1978 C20 with SM465 disassembled

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Gijordan07

Junior Member
Joined
Mar 20, 2021
Posts
5
Reaction score
1
Location
Michigan
First Name
Jordan
Truck Year
1978
Truck Model
C20
Engine Size
5.7L
I inherited a 1978 C20 from my grandfather. He parked it about 25 years ago after an unknown transmission issue.

I've already got the engine running again (that was pretty cool to fire it up) but now need to get the transmission reassembled and put back in.

The issue is that he had the original SM465 2WD pulled out and disassembled. He also evidently had another transmission he must have purchased for parts, which is also disassembled. I'm not sure which internals went to which trans, and I do know that not all SM465s are the same depending on 2wd/4wd and slight changes over the 20+ years they used them.

Can anyone help me figure out which of these is the correct 4th gear? The one with the seal and plastic thing on it doesn't seem correct... but it's not chewed up on the tips of the teeth like the other one. Also not sure where it came from if it's not from one of the two disassembled transmissions, or where the other 4th gear went..

The speedo gears are also slightly different.. not sure which one is correct for 1978 c20 - what do I need to know - rear end ring gear?

Any help is appreciated.
 

Attachments

  • 20240724_203225.jpg
    20240724_203225.jpg
    122.3 KB · Views: 23
  • 20240724_203220.jpg
    20240724_203220.jpg
    173 KB · Views: 19
  • 20240724_203336.jpg
    20240724_203336.jpg
    176.4 KB · Views: 19

Dmack

Full Access Member
Joined
Mar 13, 2019
Posts
334
Reaction score
437
Location
Central OR
First Name
Dave
Truck Year
1983
Truck Model
K20
Engine Size
350
No help on the internals, but since they are basically bulletproof and not rare, I would just look for a cheap used one. But good for you for using what you have.
 

pduffyd

Full Access Member
Joined
Sep 27, 2019
Posts
203
Reaction score
271
Location
Melbourne, Australia
First Name
Paul
Truck Year
1975
Truck Model
C20
Engine Size
454
Hi gijordan07.
When I rebuilt mine a while back this guy took you through step by step.
Site down with a beer and watch part 1 and 2.

xc_hide_links_from_guests_guests_error_hide_media

xc_hide_links_from_guests_guests_error_hide_media
 

Latest posts

Forum statistics

Threads
44,164
Posts
950,695
Members
36,277
Latest member
chevyBlu
Top