Cross member location help!

[smitty77]

Now that spring is here I'm trying to get my '79 K10 back together and ran into a snag.  In order to paint the frame and fix the brake lines, I pulled the motor and tranny/t-case and set them aside (350 SBC, 700r4/NP208 not original to the truck), fully expecting to put them back in once the frame was done, so I didn't take measurements.  But in the fall I scored a parts truck and nabbed a known-to-be-working TH400/NP205 combo, so I decided to use that tranny/t-case instead.

I have 2 sets of holes already drilled in the frame.  I know the 700r4 was mounted in the rear pair of holes.  I believe the front pair is for a TH350/NP203 that originally came with the truck.  The problem is, neither pair of holes seem to locate the TH400 in the right place.  The first location (closest to the front) had the front driveshaft "bottomed out", and the 2nd location looks much better but the tranny still looks too close to the motor mounts.

Can anyone tell me what the distance should be between the motor mounts and the bell housing (or even the flywheel)?  Specifically, the distance from the rear of the motor mount bracket on the block to the flywheel would be helpful.  I tried to measure the 350 I have sitting in plastic, but the best I could do was "somewhere around" 14".  My tranny currently sits 12.5" from the mount, give or take.  I could get 13" with the play in the holes in the motor mount.

If that 14" is true, that means I need to move the tranny 1" - 1.5" to the rear.  In another forum I found a post stating the tranny lengths as follows:
TH350    = 21.75" long
TH700r4  = 23.5" long
TH400    = 24.5" long

Do these seem right?  The present holes in the frame sit about 1.5" apart, but it looks like the hack that modified it before did them by eye.  I think I'm correct, but am looking for a second opinion from the knowledgeable folks out there before I make swiss cheese out of my frame.  I'd like to have the cross member locked in place before I swap in the motor, but worst case I just leave everything suspended and tackle it all at once.

Thanks,
Matt

[martin79]

  Can you measure the parts truck mount locations............can you find a truck with that combo to measure..............do you have a 4x4 shop where you could go talk to a mechanic ?

    You may have to suspend everthing in the right place and build to suit.........fabricate,if you are able.....hope you get er done !!

[Captkaos]

All motors are going to mount in the same location if it is a V8, just bolt it up and use the trans and mount as a guide for the holes.

[smitty77]

  Can you measure the parts truck mount locations............can you find a truck with that combo to measure..............do you have a 4x4 shop where you could go talk to a mechanic ?

    You may have to suspend everthing in the right place and build to suit.........fabricate,if you are able.....hope you get er done !!

That's what I was afraid of.  I'm working on this by myself in the driveway, and was hoping to have the tranny in place before I swapped the motor in just so I didn't have a bunch of weight propped/suspended in air.  Luckily I won't need any fabrication, just 4 new holes to mount the crossmember.  It just would have made life a tad easier, but I can deal.

As for the parts truck, it had to be scrapped as soon as I got it.  I feared trouble from the town if truck #3 showed up as I'm only supposed to have 1 unregistered vehicle, and I'm currently at 1.5.  So I pulled the hood and fenders, dropped the tranny, and cut the axles loose while it was sitting on the car trailer in my buddy's yard.  When we took it to the scrap yard, you should have seen to look on the fork operator's face when he went to pick the truck and a bunch of stuff stayed behind.

Thanks for the replies guys!
Matt