Does anybody know if the front crossmember with the strut mounts is the same on a 1/2 ton vs 3/4 ton 2wd frame? This is on a 75 D100 I have that the front crossmember is badly bent. Found a guy with a 1983 3/4 ton he is parting out.

I believe it matters how heavy duty the 3/4 ton was. As I understand, there were 2 different frame heights between the D100 and the D300, and there was also a difference in the thickness of the frame rails.

One would suspect the taller frame could have the rivet holes in different locations on the frame rails, and the crossmembers for the tall frame may not fit between the flanges of the short frame rails. If the 3/4 ton crossmember fits height wise in the 1/2 rails and the rivet holes line up, I would think the difference in the thickness should be pretty easy be adjusted for.

I'm not sure about the engine crosmember being different due to frame height but...

It is different depending on light or heavy duty suspension. The heavier setup used bigger bolts on the lower control arms..

I believe the front crosmember where the strut rods anchor is the same.

Does the seller have the lower arms or tie rods for identification?

I answered this question somewhere did you post elsewhere (nother forum maybe?)
But yeah there were 3 different "3/4 ton" gvw's most years
And the heaviest was basically a 1 ton.
The heaviest 1/2 ton was a heavier rating than the lightest 3/4 ton, even with 8 lugs vs 5.
The lightest 3/4 ton usually had a 9-1/4 rear only with 8 lug flanges. Not the Dana 60 most people think about when they think 3/4 ton.
And the heaviest 3/4 ton had a Dana 70.

I remember in the front end parts catalog the heaviest 3/4 tone wa listed with "unequal length inner and outer tie rod ends. The light and mid rated 3/4 had same tie rods etc as a 1/2 ton.
Most common was the middle of the 3 choices,
I know I. 83 at least the mid grade 3/4 ton was a 7500 GVW and the heaviest was something like 8600. I'd have to dig out one of my FSM's to see wya the light weight one was... The one with just a 9-1/4 rear...

This is why I asked about tie rods. The light duty suspension was used on ALL trucks depending on how it was optioned. Including some 1 tons. But ALL half tons got the light duty. MOST 3/4 tons got the light duty. M9ST 1 tons got heavy duty.

The 2 quick ID are tie rods and lower control arms.

WARNING GVW stickers are highly misleading. Some of the ratings are so close it can be either. Look at the parts.

I will have to get some measurements when I can (truck is in storage right now) But it, sounds like there is a good chance it will fit. Thanks for the info.