These braces are 2wd pieces, although guys have modified to fit the 4wd W series 1st gens. The 4wd braces is a much smaller mount that spaced the gear box out on frame.
Apparently late 80s and early 90s got the brace.. my factory 85 2wd frame never had the Brace and never cracked.. when I had an issue with the frame I swapped to I install this Brace and a pair of wing plates from far from stock.. no issues since.
Man I've seen some janky stuff.. but this 1.. hum. It almost seems like these springs are for the wrong year car, or something else needs addressed vs just adding extension blocks to get proper length.