Tail gate glass is broken . Will one from a 1984 Suburban work ?
Judging from the pic of the yellow blazer I'll assume that it is between a 1973 and a 1979, based on the round headlights, 1980 looks the same but has square lights, the rear glass will work in the blazer, at least I am 99% certain it will. A free easy way to make sure is to go to LMC truck parts web site and compare the part numbers for the suburban and the blazer.
Search Chevrolet Blazer Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet Blazer Experts