i just swaped in a 88-up new body aluminum/plastic tank rad in my 81-87-91 ride. only diffrence is the rad cap/neck is taller than stock.
in my truck i had short rad to begin with and the rad hold down brackets that dont bolt on top but on back side of coresupport . i used a 88-up c2500 350v8 rad i had in stock and found it bolted in no problems. it in and works. so i have a cheep alumin rad to help cool better .
the only reason i forsee any problems with 73-80 trucks running this is the coresupport might be to short and when you close the hood it might hit the cap/filler neck.
i will get pics and post up .
in my truck i had short rad to begin with and the rad hold down brackets that dont bolt on top but on back side of coresupport . i used a 88-up c2500 350v8 rad i had in stock and found it bolted in no problems. it in and works. so i have a cheep alumin rad to help cool better .
the only reason i forsee any problems with 73-80 trucks running this is the coresupport might be to short and when you close the hood it might hit the cap/filler neck.
i will get pics and post up .
(I spent the $120 to have new plastic side tanks put on instead). 
I couldn't figure out why a slightly wider one cost so much more... The narrower one was a whole bunch cheaper.