As some of you know, Im getting ready to swap out my transmission-transfer case for a nv3500 and a np231.
I have to drop the y pipe and the studs are orig. (87 truck 82,000 miles) Needless to say, they have rusted thin. I feel sure they will break. That being said, it would seem, that taking the exhaust manifold off of the truck to then replace the studs would be easier, provided the engine bolts holding the manifold come out.
My queston is, any suggestons on pulling this out? I know if I break a bolt in the head, its turned into a major job at this point........
My thinking is, to get the motor hot, and then try backing the bolts out. FWIW I have a torch that I can heat with if needed.

 

You shouldn't have to remove the manifold to deal with the y pipe connecting bolts. I cut mine with a torch between the two pieces that bolt together.
The new ones come with a piece designed to prevent the top from spinning as you tighten the nut on the bottom. I used an 18 inch extension from the bottom. The hardest part was getting the nut started.
If you decide to remove the exhaust manifold the best method is on a cold motor to heat the bolt head to cherry red then when it cools to normal color back it out. Same goes for the nuts on the studs. A Propane torch won't have enough heat to heat up just the bolt head to cherry red and would likely defeat the purpose by heating the whole area up. With oxy acetylene it heats up in like 30 seconds or less. There are videos of this on YT.

 

93 RT, like onemore94, I'd avoid removing the exhaust manifolds. Could get more trouble than you need.

The flange bolts that attach the y pipe are tough to get to, but with the right tools, you can reach them. As I recall, I bought a set of short boxed/open end wrenches from Harbor Freight and was able to wedge the 9/16's wrench against the pipe on top, then I used an extension to reach the lower nut. If they won't turn off they'll probably break, either way you win. A breaker bar may help, and I always find cussing helpful too.

Take a good look at the bolts and figure out if there's a tool you can buy that will make the job easier. Offset wrenches, short wrenches, stuff like that, can help a lot. I love Harbor Freight for that kinda thing.

 

I provided my experience in case he chose to or had to. I happened to have to replace broken studs on mine. There is a thread on here where I describe the job. It's not as hard as it seems at first if you are good with power tools. The stud holes are deeper than the stud is long for exactly that reason and the replacement studs are a 1/2 inch longer on the outside too. So damaging the first thread isn't as dire a problem as it might seem. Have the right sized thread chaser ready if that is what you are doing.

 

You know, I need to look at that again. I thought the bolts holding the y pipe to the manifold were studs. I was thinking I would have to remove the stud from the manifold. Sorry, I should have looked again before posting.

 

I didn't realize the manifold threads went that deep, that's good to know. Likewise with the extra length on the replacement studs. Thanks for that info.

Oh, if you do pull the manifolds, you may find they don't have gaskets. From what I understand, that's how the factory assembled them. But after so many miles those exhaust manifolds can warp, so consider putting on some FelPro exhaust manifold gaskets, just in case. That advice pertains even more to the longer V8 manifolds.

 

I think I worded that in a way that may mislead.
I meant to indicate that the threaded hole is longer than the half of the stud that is meant to go into it. That length of thread on the 3.9 is around a 1/2 inch and I estimated the hole is at least 1/4 to 3/8 longer. It is not as I wrote longer than the stud itself.
The threads are different on each side as well. I forget exactly but want to say the head side is fine threads and the outer side where the manifold mounts is course thread.

 

Heh. Other way around.

Block is 5/16-18; the other end is whatever the stud is (in case you get one that's all coarse, or coarse/fine, or just go to bolts.)

I had the opposite problem - my studs kept working loose! But I THINK that's fixed with enough heat/cool cycles.

RwP