crooked crossmember/ warped frame???

[Liltroy]

hey guys I need some help/ opinions please. I have a 74 stepside and just dropped the transmission(th400) to replace the front seal. when I was unbolting the crossmember it seems that the passenger side uses the factory bolt holes but the drivers side is about an inch back and has had new holes drilled. The tail of the trans seems to be centered between the frame rails so the only way I can see that this would be possible is if the frame was slightly tweaked on one side??? If I try to slide the crossmmber forward an inch on the drivers side to match the factory holes then the trans mount doesnt quit line up with the holes in the crossmember. Where can I take measurements to figure out if one side of my frame is pushed back(possible from a front end hit on one side) or if the frame is warped somehow? Any help would be appreciated.

 

[kleedus]

my first thought is your truck originally had a turbo 350 and someone swapped in the 400

the 400 is longer than the 350 so it would need the holes in the frame farther back

I would bet someone forced the cross member to bolt up on the one side and just drilled new holes for the other so the cross member would be crooked

I would bolt the cross member to the mount then get it straight on the frame. so the cross member is straight then drill new holes

 

[DanMcG]

Here's a link to another site with the frame spec's..
http://www.chuckschevytruckpages.com/framespecs.html

I'm not sure if links to other sites are frowned on here, if so delete it.

 

[MadOgre]

Great frame info Dan.

I would be cautious of drilling to many holes too close together for the tranny cross member. Or invest in a 1/4 plate to install above and below the frame with the correct bolt hole dimensions of your cross member. 4 in total. Kinda like giant size washers.

 

[HotRodPC]

Yep, it should be a Th350.

 

[Liltroy]

i understand the th350 suggestion but the issue i have is that the crossmember doesnt look crooked despite the the fact that its bolted back an inch on the drivers side thats why i was worried about the frame. ill crawl under there and take measurements to see if it is in fact crooked. thanks for the link and suggestions guys.

 

[Liltroy]

ok i have confirmed the truck originally came with the th400 so thats not it.

 

[bucket]

Can you post a picture of the issue? If new holes were needed because the frame was tweaked, it should be plainly obvious. Maybe the holes are factory and somebody hogged them out for larger/incorrect bolts?

ok i have confirmed the truck originally came with the th400 so thats not it.

Out of curiosity, how did you confirm this?

 

[Liltroy]

options tag in glovebox says m40 which is th400 transmission. a th350 would have had rpo code mx1. at least thats what everything Ive been able to find says. I could be wrong but everywhere Ive looked says rpo code m40 is for th400 3 speed auto.

 

[chengny]

Here is a picture of the frame and mounting/bracketing stuff:

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I could be wrong but everywhere Ive looked says rpo code m40 is for th400 3 speed auto.

You're not - wrong.

M40 76 88 TRANSMISSION,3-SPO AUTO (THM400)