1973-80(all round headlights till about 80 or 81 they had a cross off a square headlight and turn signal from the old) all interchanged body parts and suspension,However their were alot of diffrences in trims through out these years though doorshells from 73-80 would fit the 81-87 Chevy,Gmc Trucks,suburbans and k5 blazers the internal door parts were diffrent the hoods and fenders are a diffrent style though you can run a Front clip from a 73-80 chevy, gmc truck, suburban and k5 blazer on the 81-91 chevy,gmc trucks with out any huge modifications you can not run an 81-91 chevy,gmc truck suburban,K5 blazer front clip on the older 73-80 trucks or suburbans,k5 blazers with out modifying the cab in some way to accept the diffrent hood hinges.
1981-87(single headlights or stacked 4 headlights) Chevy,GMC Fullsize Trucks,Suburbans and K5 Blazers parts interchanged Hood,Fenders,Doors,Interior parts.1988-91 Chevy Gmc Fullsize k5 Blazers and Suburbans all shared alot of interchange also.1987 was the last year of the Box style for the half ton chevy and gmc trucks though the 3/4 and 1 ton chevy and Gmc trucks stayed with the box style all the way to 1991 such as a crew cab long bed or a std cab cab and chassis.1988 chevy gmc suburban was the last year of the stacked headlights for the Suburban and K5 Fullsize blazer and changed to the side by side headlights 89-91 though their was a single work truck headlight system with a newer style grille)for the suburbans and k5 blazers.The square body blazer was discontinued and replaced with the 88-98 half ton truck front end but was still called a k5 but thats a whole another beast hahahah.The suburban changed body
styles in 1992.
The 81-87 chevy suburbans and k5 blazers have diffrent tailgates though they look similar the k5 blazer tailgate power window is a plastic chain drivin and the suburban tailgate window is a regulator with a motor like a normal power window in one of the doors.Personally i will never understand why Gm didnt do the k5 the same as the suburban.Hey anythings possible.
Though i have to say the 20 year interchange makes for some ease of building and repairing these trucks.I hope this helps
Beds from 73-87 interchanged though the gas door was diffrent on 73-80(round) chevy Gmc trucks and 81-87(square) chevy gmc trucks.
Tailgate styles were also diffrent through the years depending on the trim package.But all interchanged for the fleet side longbed or shortbed.
1955 2nd series Chevy trucks and Gmc trucks with the stepside bed Carried the same tailgate style all the way to 1987.Though the bed sides and fenders were diffrent thats a little tid bit of useless info hahahah.
