Gas tank interchangeability

[93w/t1500]

Well the weather finally broke in upstate NY and that means it's time to work on my '84 K10 Suburban (350 4bbl, SM 465, NP208). My current project is the fuel tank and sending unit as the sending unit is pretty rotten and started leaking. The current tank is marginal at best so I hit the junkyard this weekend and found a suitable donor tank out of an '86 Suburban. I got it out and realized that it's quite a lot bigger than my current tank. I did some measurements and it's the 40 gallon tank: my '84 came with the 25 gallon tank. From what I can see it looks like a direct bolt in replacement, needing only the 40 gallon tank straps and a 40 gallon specific sending unit. Did GM make any frame changes to accomodate the larger gas tanks? Has anyone tried this replacement/upgrade?