From my thread...
I've done some cursory measurements, and also checked online. There are three sized tanks that the Suburbans came with:
25 Gallon: 28-3/4" x 28-18" x 10-3/4"
31 Gallon: 28-3/4" x 28-18" x 12-3/4"
40 Gallon: 35" x 28-3/4" x 13-1/8"
(Sizes verified on LMC Truck, O'Reilly & Napa Auto websites)
I decided to go with the square-body suburban 31 gallon gas tank. That required a little bit of fabrication on the back end of the truck.
To start, the rear cross-sill (the one with the light plug) came out, and was rotated 180-degrees, and became the front brace for the fuel tank.
This effort was followed for quite some time with lots of measurements. I needed to have the fuel neck clear the frame, but at the same time not be so tall as it would bump into the bottom of the bed. Likewise, I needed to play with it front-to-back as so to sit between the bed rails. Once that was done, I finished the calculations and made the brackets.
Then it was a matter of getting it into its final resting place.
***Note: The rear brake line is a temporary solution, and will be getting adjusted either today or next weekend. I'll re-work the bracket and provide more substantive support across the frame before joining to the soft-line on the axle.
