1968 GMC - Ol' Blue

[cornerstone]

It'd be a shame to scratch that bed floor! I'd rather buy a new truck to work with than watch all my hard work get tore up. If it were mine, of course. Your paint is a work of automotive art!

[MDPotter]

My dad and I entered in or first car show last weekend. We didn't win any awards, but didn't go expecting to either. There are lots of guys there that travel quite a ways with very nice and rare cars and get there early to get the right spot. We did meet a local guy that's into C10's and also talked to a couple guys that needed a little inspiration to work on their own projects which is more important than winning a trophy.

It's a mystery how sometimes things happen when they do. A few days before the show, I walk out to the garage and there's a puddle of ATF under my truck. The first though that comes to my head is tailshaft seal. Then I go down the rabbit hole on the internet about that, or the tailshaft bushing, is it right seal in the first place, and eventually I find a post about a "welch plug" that sometimes exist in transmission yokes. So I slid my body under the truck (I don't have a jack at my house-I think that's what I'll ask for Christmas) and did some investigating and found that there is a pinhole in the center of the yoke and the ATF is seeping out of it. So I cleaned it up and applied some RTV and it seems to be fixed. I don't know why after so many months it started to leak. I hadn't driven it in about three weeks - maybe the fluid slowly crept towards the tail shaft? Regardless, it was an easy fix.

Still happy with the truck. There are things I want to do to it, but nothing that's actually important. I would like to convert to coils in the rear to get it a little lower and to ride better, convert to 5 lug so I can get the wheels I want, get A/C, and reclear the hood. Just not a priority for the foreseeable future.

[clay68c10]

Looking good!
On your trans leak; there is an o-ring on the output shaft that can cause that leak. If you look at the inside of your slip yoke, there's a smooth area before the splines where that o-ring sits and seals the splines. It's an easy fix, just pull the tail housing to get to it.

[MDPotter]

Originally Posted by clay68c10

Looking good!
On your trans leak; there is an o-ring on the output shaft that can cause that leak. If you look at the inside of your slip yoke, there's a smooth area before the splines where that o-ring sits and seals the splines. It's an easy fix, just pull the tail housing to get to it.

Thanks for the input, I might get into it someday. It hasn't leaked since I applied the RTV and I just chalk it up to my truck telling me it needs exercise.

[jasinger01]

Love the build!! What are your overall thoughts on the drop leafs? I have a 69 GMC that I'm torn on. Stuck on drop leafs vs a DJM flip kit. Ideally I'd like 4-5" drop, and I'm afraid a flip kit may be too low.

[MDPotter]

Originally Posted by jasinger01

Love the build!! What are your overall thoughts on the drop leafs? I have a 69 GMC that I'm torn on. Stuck on drop leafs vs a DJM flip kit. Ideally I'd like 4-5" drop, and I'm afraid a flip kit may be too low.

They're okay. You may have noticed, but I had a super thick pack of leaves and even with 4" drop springs I dropped somewhere between 3"-4". If you want 4-5" of drop, I would go for the flip kit. I expected and wanted more drop and might have to convert to coils someday to get the ride height I want and a better ride. Worst case, the flip kit is too low and you're out $100 or so and you sell the kit.

[jasinger01]

Originally Posted by MDPotter

They're okay. You may have noticed, but I had a super thick pack of leaves and even with 4" drop springs I dropped somewhere between 3"-4". If you want 4-5" of drop, I would go for the flip kit. I expected and wanted more drop and might have to convert to coils someday to get the ride height I want and a better ride. Worst case, the flip kit is too low and you're out $100 or so and you sell the kit.

Yeah, I think that's the rationale I'm leaning towards. Can start with a flip kit, which is entirely reversible and a fraction of the cost of the drop leafs. I'm working on the front end now with drop spindles and drop coils so once I finish that, I'll see how it sits and make a decision on the rear. Seems like everyone that has a GMC has to go through this decision on the rear suspension!

[MDPotter]

Originally Posted by jasinger01

Yeah, I think that's the rationale I'm leaning towards. Can start with a flip kit, which is entirely reversible and a fraction of the cost of the drop leafs. I'm working on the front end now with drop spindles and drop coils so once I finish that, I'll see how it sits and make a decision on the rear. Seems like everyone that has a GMC has to go through this decision on the rear suspension!

Yes, that's the drawback to having a GMC. Leaf springs make it harder to lower and the ride isn't as nice. I bet you end up happy with the flip kit if you're going with drop spindles and coils.

[TA_C10]

Originally Posted by clay68c10

Looking good!
On your trans leak; there is an o-ring on the output shaft that can cause that leak. If you look at the inside of your slip yoke, there's a smooth area before the splines where that o-ring sits and seals the splines. It's an easy fix, just pull the tail housing to get to it.

Hey, catching up on threads been forever. Clay is right, and I'm surprised you didn't see me fix mine. Same exact issue. Hole in yoke. ATF puddle one day. Go check out my post in build thread if you want I explained the whole thing. I think lol. And i also went down that rabbit hole. Turns out there are different output shafts on same trans for different uses cases. Long story short, if you got a yoke with the weep hole, you need the rubber o-ring on output shaft. If you don't have the weep hole, you don't need the o-ring. Something like that

Now get to work, I expected more updates on this thread...

[TA_C10]

Found it, post 628, link below.

https://67-72chevytrucks.com/vboard/...&postcount=628

[MDPotter]

Originally Posted by TA_C10

Hey, catching up on threads been forever. Clay is right, and I'm surprised you didn't see me fix mine. Same exact issue. Hole in yoke. ATF puddle one day. Go check out my post in build thread if you want I explained the whole thing. I think lol. And i also went down that rabbit hole. Turns out there are different output shafts on same trans for different uses cases. Long story short, if you got a yoke with the weep hole, you need the rubber o-ring on output shaft. If you don't have the weep hole, you don't need the o-ring. Something like that

Now get to work, I expected more updates on this thread...

Originally Posted by TA_C10

Found it, post 628, link below.

https://67-72chevytrucks.com/vboard/...&postcount=628

Thanks for posting this. If it happens again, I'll have to dive in deeper. Smearing some RTV over the weep hole in the yoke has held up so far!

I'm still dreaming of wheels/tires/5 lug conversion/truetrac/3.73 gears. Maybe someday...