different yrs had mods to them like the notches on the 1s in pics.

some clearance for cooler lines ect..

as far as I have seen they are 904/727 specific sb & BB specific truck & car specific.

I have ditched a lot, had a lot that would not bolt up correctly and have had 1 & 2 installed with headers...most times A-body headers they got ditched.

they come in handy to chop up and make torque straps from engine to frame rail on the cheap.

and I have seen them used on the 4x4 xfers with skid plates to keep from busting the cases.

ma mopar fixed a huge problem on the cheap by stamping out steel trans braces by the thousands.... same as the steering box brace used on late 70s early/mid 80s trucks for cracking frame holes at steering box.

run them if you got them.