kilroy---kind of in the same spot as you ----putting a 6bt into a 71 dodge truck---the 89-90 dodge diesel radiators are not all that big--i layed it flat and poured in 5.5 quarts---my possible radiator will be a 80 dodge truck aluminum aftermarket and it holds 1 gallon---having a custom made radiator will run around $500----my hot rod buddies buy circle track radiators from speedway for less than $200 to put into 30,s cars---if you check speedways catalog it will give you all the dimensions----bob