Crossmember & adapter question

[Taylormade]

I replaced my 700R4 with the stock crossmember and short adapter to a TH400 with a flat style xmember and a tall adapter.

Since the new height, my driveshaft is too high to reach my rear axle (length is fine).

My question is, can the short TH400 to NP208 adapter fit the flat crossmember?

 

[dyeager535]

No, and AFAIK you should have no difference in height.

Someone here may know if there was a difference 1973-1980, but the 1981-1984 flat crossmember should put the output in the same place as the '85+ "short" adapter crossmember.

I ran my truck originally with the tall adapter/flat crossmember (1981 frame so I was told) then swapped to the short adapter/humped crossmember and nothing changed in relation to output shaft.

Using the flat crossmember and short adapter would cause all sorts of issues.

Do you have the right adapter mounts for the early style adapter?

 

[nvrenuf]

I replaced my 700R4 with the stock crossmember and short adapter to a TH400 with a flat style xmember and a tall adapter.

Since the new height, my driveshaft is too high to reach my rear axle (length is fine).

My question is, can the short TH400 to NP208 adapter fit the flat crossmember?

Did your "flat" crossmember come from a 1 ton?

 

[Taylormade]

I believe that the crossmember came out of a 1ton.

There is significant height difference, Dorian, as compared to my other setup.

 

[nvrenuf]

1 ton crossmembers are different from 1/2 and 3/4 tons. A straight crossmember from an '84 or older truck is what you need for your tall style adapter. These hanger lower than a 1 ton straight crossmember.

 

[Taylormade]

Thanks John, Ill start looking!
Picture for reference, I noticed while taking the pic that the top of the TC was less than an inch from the body, and that is with a 1" body lift...

 

[sweetk30]

don't run the spacer tubes like that between the frame . they are for the top of the frame only . over time it will blow out the frame rails .

and yes you need a 1/2 or 3/4 ton crossmember .

true 1ton frame is about 2" lower in the area were the crossmember mounts up = flatter crossmember.

 

[Taylormade]

I have always heard that, k30 about running the spacers on top. I just can't see how there would be any difference if I ran a flat washer on top. I would swap them, but I setup my pinion angle based off the spacers being on the bottom.

 

[dyeager535]

Are those big oblong holes in the frame from the x-member bolts??

 

[sweetk30]

its the extreme pressure in a pin point area .

the spacers were used to give the bolt room to flex and stay tight when the frames flexed . that's why there on top .

if you need to space down do it with a piece of solid stock and or thickwall square tube . this will spread the load out on the frame rails a lot better .

 

[Taylormade]

Yeah, I'll do that. That sounds like a better idea than washers.

The oblong holes are from having to re drill the holes for the crossmember.

 

[Taylormade]

I fixed the issue by going back to my stock crossmember and using a short adapter. Thanks fellas for the help!