Over 4 years ago, I installed a Cummins 6BT in my '79 F250. At the time I was so excited to drive it I hooked up the fuel and return lines to the front tank with about 6' of hose, thinking I would plumb the rear and do it right in a few days. 50,000 miles and nearly 5 years later I finally got it done. For the past few days, I have had several gallons of diesel run down my arms and at least a pound of dirt in my eyes doing it right. I installed stainless steel fuel and return lines to both tanks, installed a fuel valve from a '90's Powerstroke, and installed and wired a new double pole/single throw switch from NAPA.

So now I have a '79 F250 with
'89 Cummins
'79 F350 D60 front
'94 NV 4500 transmission
'89 Dodge 3.54 D60 front gears in my Ford D60 rear axle
'97 Ford F350 D60 3.54 front gears in my '79 front axle
tons of parts from several Ford and Dodge parts trucks (I don't think I have any chebby parts on it)

I have kept a note book of what I have used so can go to the parts house and get parts for the right year and model truck to repair anything that comes up. Most parts are on the shelf.