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Discussion Starter · #1 ·
I have yet to find out about what my truck (1981 C10) at home has in it besides I know it has a 305. Just found out there is a leak (tranny fluid) so I know I will have to drop the pan and such but since I will be under for a bit what are some good things to go ahead and swap and change and check on in the rear end and the transmission?
 

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Do you know which trans is in the truck yet…places that the GM trans will leak are pan gasket, shifter seal, accumulator cover gasket, output drive shaft seal and front pump seal…the last one you will not be able to change..the ones in bold are notorious leakers on a th350 id the trans before buying any gaskets..as far as the rear axle to id the axle there are a series of letters and numbers on the top right rear of the axle tube, you may have to use sandpaper lightly to revel them thru the rust..get those and we can help you id it..
 

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Discussion Starter · #3 ·
I don't have any specs yet. Still in Africa for a bit until Mid Sep. I will have to get her to crawl up under anim_63 I just wanna have some sort of idea so Im not trying to play catch up when I do get home. I hope it is just the pan tho for the leak it seems easy to fix and not expensive. But thank you for the info!!! Nice to start learning this stuff!
 

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FYI
If its the seal at the shifter there is a tool to change it with out taking everything apart. Cheap too.
Yes I just bought one not to long ago, replaced mine….so easy it takes all the fun…( language ) out of it….anim_63
 

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Discussion Starter · #7 ·
Im home now and finally got to get under and see whats going on. I have a GM12 rear end I think.. But thats the only markings I could find on it. Not sure if thats a normal rear or not. But as for the transmission. Its a Th350 and I think I found what happens to be the issue...? there was about a Quart of trans oil on the floor. . I went to pull it out of the garage where my wife parked it and it will not turn the tires in any gear. Im thinking its the torque converter. It looks super rusty too.. Should I replace the Flex Plate too?
 

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Rear axle id numbers are on the right side axle tube on the top rear, use sandpaper to reveal them but don`t get to aggressive with the sandpaper…tranny is a whole issue in itself, if your going to replace the tranny or have it out, replace the flex plate its cheap insurance, torque convertor the same, replace if going with a rebuilt trans..
 

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I have the same problem with the tranny on my 1980 SSG . seems like the only time it dont leak is when I drive the truck, the rest of the time I have a puddle underneath of it of ATF and when I dont drive it for awhile it wont move at all.

Im thinking of replacing the TH350 with either a 700-R4 or a 200-4R since Im going to be driving the truck on a regular basis.
 

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Discussion Starter · #10 ·
I am thinking of getting a new one too. Not sure whats the best one, I have a 305 in it which I know not to many people like but it seems to be solid for now. But have to get the wife on board with the purchase haha Also trying to sell my Ranger I have; I need to do this first before I can get real deep into it lol
 

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Well when I'm looking for a leak I use a clean large peace of card board. I place it under the area and watch where it hits. This doesn't always work because some leaks drip and run down on other parts but it gives you a starting place. Also mentioned if your changing the trans for any reason change the torque converter too. If the trans is bad dirt rust anything it is in the converter you don't want it in the new trans. Good luck guys and have fun
;)
 
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