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 .