HAHA for the title. Im refering to the back of the motor where it bolts up. Does anyone know if the block sticks out anymore then a LT1, which would cover the flex plate more?

 

the bolt pattern is different. but mostly the same. you can bolt an oldschool trans to the LS1 pattern all but 1 of the old bolts. tons of people have run th400's/th350s that way w/o any prob.s that Ive ever heard of. I know the torque conv.s are different between LT1 and LS1, so it could be that the bellhousing is machined to a different depth, or that the crank sticks out toward the conv. more with an LS1. why do you ask? maybe someone knows the answer you really want. cant think of any other reasons why youd wonder your question.
chris

 

th350/400 can be used on ls1 with stock 6.0 truck flexplate and
spacer that comes with flexplate, about .410 thick. with use of
10' dual bolt pattern tq conv. for th350/400
one bolt is missing, diff. position of bolt holes on ls1 block
fastens with only 6 bolts

 

the conv. you mention, is that spec'd for SBC? thenI wonder if same dual bolt pattern 700r4 stall would work with a 700r4 tranny behind LS1?

 

non electronic 700r4 from 3rd gen type cars will work and can be adapted
to be used with ls1 engines, if the converter uses the th350/400 bolt pattern
non lockup converter