4x4 1/2T vs. 3/4T vs. 1T frames

[Elpresidente]

From what I understand, 1/2 & 3/4T frames are the same size but 3/4T is  ~.050" thicker; and 1T is slightly taller and made of even thicker steel. So will 1/2T suspension fit on a 3/4T frame? and will 3/4T and 1T suspension fit the same on both frames? Its a bit confusing, im just wondering what suspension will fit certain frames so when I go looking around for I know what to expect for the build.
Thanks.

[Captkaos]

the difference in suspensions for the most part is the springs.  3/4T suspensions were available on the rear of 1/2T trucks, they were HD 56" long springs, so if you have 53" springs, you have to move the spring mount to use the 56" springs.  All 3/4T and 1T trucks used 56" springs, 1/2T used either 53" or 56".  on the front, they springs are the same, only difference is the rate.

If you have a 1/2T truck with 56" rear springs, a 1T set will bolt in.  Even if you had 53" 1/2T rear springs, the axles off a SRW 1T will bolt up to the springs.

[Elpresidente]

Excellent, thanks.

[werewolfx13]

I know my '76 k20 title and frame to be a match, and its a 3/4t 4x4 with 53" rear springs....6800 lb GVWR. I'm the third owner, bought it from my uncle, who bought it in 1986 from his neighbor of  (at the time) 12 years..he saw the truck in its original form come home from the dealer...Only changes ever to happen to this truck (including chassis lubrication!) came about after my uncle bought the truck. Any chance some of the light duty 3/4 tons came with the shorter springs? My evidence points that way..