A few questions about 87 R10

[xonair]

well some of you know that 87 was the first year of the TBI in a c10 and so they called it a R10. I have a few questons. The truck came with a TH400 but I am leaning on installing a 200r4 transmission for the over drive. No I am not going to do a 700R4 since I will need to modify my frame [new frame built] . the 200r4 Mounts the same as the TH400. The only problem is it seems to be a bit shorter. Does any one know the allowable length of a one piece drive saft before having to add a split drive shift? Also does anyone know the actuallength of the Th400 in this truck. I see the tail is fairly long, but can't find anything online with the longer tail length.

[sierra4x4]

I have a couple 87's and both of them have the Th375 trans. Are you sure thats not what you have becouse usually the Th400 uses a short tailshaft and a fixed yoke a with a 2 peice drive shaft. The Th375 uses the same yoke as a 200r4,th350 and 700r4.

[Keith Seymore]

Drive shaft length is a function of rpm, which depends on how fast you plan on driving, rear axle ratio, etc. You can also compensate for length by using "premium" materials, like aluminum or carbon fiber (as opposed to steel).

I would suggest you figure out the overall length required and then ask a local driveshaft shop what they would recommend.

If it was me I'd probably just have a one piece steel shaft made and be done with it, but I would not be racing it or driving much more than 70 mph. I'm not sure what your actual usage would be.

K

[Desert1957]

This is my understanding of the transmissions in the 87's and I don't know whatever other years. Many years ago (As told by my transmission Guy) Gm ran short do to a strike , or parts problem with their Longshaft "350 Turbo's" during the middle of the production run. They scrambled for an answer. They reto fitted there "400's" with the longer mainshaft / yoke and tail stock to fit into these trucks.
This solved many problems. First of all the crossmember could remain the same and the front driveshaft / yoke remains the same as a Longshaft "350 Turbo".

So with all that info , My guess is a "Metric 200R" will swap where a Longshaft "350 Turbo" was , So a "375 Turbo" (which is what you have) should come right out and be replaced with a "Metric 200R"

This story was also verified through my wife's family all worked at GM plants across the country for over 30+ years.

Desert

PS: My 87 375 has a two piece driveshaft with a center support bearing

[nlped]

My '87 came with an overdrive transmission. Is it a 200r4 or a 700r4. Looking at the trans pan it appears to be a 700r4, and I bought the truck from the original family.

[Desert1957]

I have never seen a 200R come in a Square Body year truck from the factory , Back when our trucks were new that transmission was WAY to light duty. Nowdays with all new advancements these (Metric 200R's) can survive behind just about any power plant when properly overhauled and beefed up.

Iv'e had Monte Carlo SS's and Buick Grand Nationals puke through 3 or 4 transimssion while still under warranty. Some of the weaknesses were Plasic parts in the Governors , along with poorly cast aluminum cases. old designs were simply a POS....

Desert

PS: My 87 has a Turbo 375 but it came as a "Heavy Half" but with a 305 TBI engine, Go figure?

[sjreno]

Well, that answered a few trans questions I had.

[nlped]

Cool, thanks Desert. I thought it was a 700r4. I did have an '86 that had a 200r4, but I'm pretty sure the previous owner put it in. It held up great though, it was just a long bed and I wanted a SWB so it had to go. My ex-wife's new husband bought it

[Desert1957]

Yea , that's the great thing about those 200's , If you had a 4 speed , Turbo 350 , or a Powerglide (if you guys even know what that is ) you could swap them for an overdrive. Direct bolt in swap , crossmember , driveshaft , and yoke all the same spline. Only a few shifter mods required for the extra detent.
I have done a few on some friends muscle cars.

Desert

[southside_jon]

I have an '87 3/4 ton Crew cab, with what I thought was a TH400. Now I'm not sure. Where the 400s used in '87? P.S. I'm looking to swap for an overdrive also. I have a overdrive trans out of a '92 1/2. would this work?

I found this website. the guy real did his homework. It might help someone.
http://www.rowand.net/Shop/Tech/Auto...issionSwap.htm

[clinebarger]

Originally Posted by southside_jon

I have an '87 3/4 ton Crew cab, with what I thought was a TH400. Now I'm not sure. Where the 400s used in '87? P.S. I'm looking to swap for an overdrive also. I have a overdrive trans out of a '92 1/2. would this work?

I found this website. the guy real did his homework. It might help someone.
http://www.rowand.net/Shop/Tech/Auto...issionSwap.htm

your truck should have a TH400. Are you saying you have a trans from a 92 1/2 ton? that will be a 700R4/4L60, with that heavy truck I whould stay with the TH400.

[southside_jon]

My TH400 is burned up. Do you know of any overdrives that would hold up. And yea the
'92 Trans is my only "on hand" opption. Until funds inprove. But I don't want to use it if it's not going to hold up.

[clinebarger]

Originally Posted by southside_jon

My TH400 is burned up. Do you know of any overdrives that would hold up. And yea the
'92 Trans is my only "on hand" opption. Until funds inprove. But I don't want to use it if it's not going to hold up.

A bench job on a TH400 is cheap, $350 to $450 aslong as no hard parts are broke.

A stock 700R4 will probably not hold up, but it depends on how you drive it.

A 4L80E will hold up. They can be installed in your truck using factory parts, but it takes time, money, and alot of effort.