yarddog

I think I'll leave the pre vp cooler in place and add a second cooler in the return line. It would be cooled a little right before it hits the VP then cooled again on the return route. As much fuel as there is to keep cool, I'm thinking the bigger the better on the return line cooler. The biggest I found on summit was 7 in. x 21 in. x 1 1/ 2 in.

Now, which style is better, tube and fin, or stacked plate?

Clunk

It might RJ, thetank is made of plastic and has even more plastic cover on the bottom for rock protection I guess.
I don't think that plastic passes heat as good as a steel tank.
The fuel module plays a part too. I haven't had one apart yet but pictures indicate that return fuel is very near the fuel pickup and gets picked up pretty quick.
A real can of worms can be opened up here...does hot fuel make more power in a diesel setting? I guess we've all heard the old OTR drivers saying a hot motor runs better.

yarddog

It does, in fact it drops it into the bottom bowl of the module right on top of the pump. When I gutted mine, I left the return hose curved to get as far from the suction line as I could.