I've been waiting for fuel system parts. That all started showing up this week. Going to make Nylon lines once the tank is in and I have a good idea on lengths.
Since the 38 gallon tanks are from late 80s trucks prior to EFI, there are no drop in fuel pump assemblies. Did some measuring and cross referenced another post on the swap.
3 lengths of tubing needed. I used Nickel Copper for all 3. Brass compression fittings make up the connections.
3/8" - 5 3/8" long (support tube)
3/8" - 5 1/8" long (feed tube)
5/16" - 5 1/8" (return tube)
Before you can drop in the assembly to check for fit, you have to modify the top of the tank. The tabs on the EFI pump assembly dont line up with the older tank. One option is to cut the tabs off but it was easy enough to dremel out new slots for the tabs on the pump assembly to still work. The tab layout is the same they just have to be orientated approx opposite of the present ones. I made a cardboard template and used it, to lay them out. The cut them with a small cut off on a dremel and filed smooth. (top set of notches in the photo)
Test fit into the tank and looks to be low enough to work just fine.
Still have to mess with the fuel sender arm to get it to fit, but a clothes hanger is almost exactly the right size to reproduce the float rod, then I have to do a bit of wiring and make a support plate since the bucket and line assembly used to directly attach and no longer do, due to the longer fuel lines.