S10 - Take Two

I measured a lot today, although I will need to go back and double check a few things before I start attacking the chassis.  I threw together a spreadsheet of various lengths, and added (and subtracted) values I needed to figure out how much shorter the chassis needs to be between the engine mounts and the rear axle.  There is also some extraneous info there (in italics) that is not included in the calculations.  U-joints between the two different driveshafts should all be the same, too, but even if adapter u-joints are needed, it should not affect the lengths.  This will not be perfectly exact, but should be in a safe range for the yoke to work without falling out of the transmission, or bottoming out in it.  If I do flub it up a bit, I have some axle plates that can adjust the axle forward and rearward a bit, but would prefer not to use them.

Here's a screencap of the spreadsheet.  Please let me know if it looks like I missed anything important, or if my math is wrong:

I also made some height measurements while the engine was in.  The rear of the oil pan sump was 16" off the garage floor.  The bottom of the chassis at the transmission crossmember was 15.25" off the garage floor. 

Pulled the engine, and returned it to its roller stands, and I tossed on the long tube headers. 

This is where I have run into a possible problem.  I had read a warning somewhere that these headers sat at least a bit below the bottom of the chassis.  However, mounted to the engine, the bottom of the end of the collector sat 10" up, while the oil pan sump sat 6.75" up.   Adding the numbers up, it looks like they will be 4" above the bottom of the frame, which will put them tucked almost against the floorpan.  Depending on the shape of the pan where the headers end, I may able to run them into an S-curve, but they may just not fit if I z the chassis, and the floor sits lower than stock.  I may grab some cheap stainless ebay shorty headers as a backup.  That would also reduce the budget hit, as these are in the $200ish range, and I could get a cheap set for under $100.  With the engine and cab set back where I intend to put them, the stock manifolds might even fit, but I'll only do that if I am really short on budget.

Oh yeah, being as there is only 24" between the cab and the front of the rear wheel, I'd need to actually cut part of the wheel well into the cab to make everything work with the S10 driveshaft, so it's a pretty good bet the Trailblazer's driveshaft will get used.

Glad to see you progressing so well. This is a hard time of year to get much shop time for a lot of people. Looking good! 

In reply to madmrak351 :

Thanks!  Being retired helps, but this is also becoming a bit of an obsession for me.  If I had more space to spread out into, I'd probably be even farther along.

I picked up a couple of 6' pieces of L-shaped steel today, and will try to weld up some rails in the near future to support the cab.  The plan is to still lift it in the center since it should be strong there, and just use some jack stands to support the rails.