NP205 / TH400 swapped in 78 K5 - crossmember issues

[reddog64]

OK, pulled the th350/203 out and put the th400 NP205 in it's place...

I had the crossmember from the donor vehicle (1 ton 84 chev truck)
It didnt work at all... wasnt deep enough...

The 203 one fits right but it's not wide enough...
seems the frame spreads out about 1.5 to 2 inches total...
the th400/205 seems to be longer than the th350/203...

so if i drill new holes, no big deal, but i'll only get one hole drilled...

it's like the frame angles back in so it goes in a slice acrost the crossmember part where it meets the frame...

WTF???

I'm gonna bolt it up with one bolt for now till i figure out what to do... need to get it out of the garage tomorrow...

help...

 

[reddog64]

Anyone ...

no one's ever put a th400 / 205 in a blazer...

 

[bigblock72]

Do you have any pictures? I can't quite visualize what your problem is.

 

[onetonbb74]

the donor vehicle crossmember from a 1 ton will not work, but if its wide enough, cut the ends off of it allowing enough metal to reweld the ends on the older 203 crossmember, then redrill new holes in the frame and bolt it in, mine (203 crossmember) is bolted on the part of the frame that starts to go up, it bolted in with a slight radius to the mounts, but works.

 

[1-tonmudder]

My 205 took the same X-member that the 203 did/does.It was in a 80 k-10 before I put the blazer together and in a 81 K-30 before that.Do you have the figure eight adapter or the round pattern??

 

[reddog64]

I have the round one i believe... the part from the adapter to the tranny is 6 bolts...

i ended up using the np203 crossmember, aligned it the best i could to center of the vehicle and drilled some new holes...

Problem being the second hole doesnt have much frame... the frame widens where the crossmember hits the frame...

 

[dyeager535]

I know what you are talking about, no one believed me when I said the crossmember I had originally wasn't wide enough when moved for the new tranny/t-case setup. I'm to the point now where my current frame has so many crossmember holes in it that I almost couldn't bolt the crossmember up this last swap without welding them all up.

 

[reddog64]

I think i'll just have to have one fabbed up...
How important is it to get the tailshaft on the 205 centered perfectly?

 

[dyeager535]

It's the same as the angle between pinion and output shaft, since you are affecting the operating angles there. I eyeballed mine, didn't seem to come out too bad.

It's probably not as important in this regard because you can't get it very far off, unless the t-case mounts have a lot of play,movement or adjustment in them.