tie rod question a body

They do interchange, but
68 to 72 are upside-downers with hooked ends.
73 up have down firing studs.
If you are going to run over-the-steering headers, it is best to use all the 73-up steering parts, including the centerlink,the pitman arm and the idler arm, and with power-steering, this usually means the steering box too... because the early box has a smaller sector shaft diameter.
If running log-manifolds this is a non-issue, run what you got; as long as you use the entire steering system.
IIRC,the 73-up centerlink provides a lil more oilpan clearance

On my 68 Barracuda,I am running 73-up steering,on my 70 KH 4-piston disc-brake spindles, to clear my Milodon Roadrace oilpan on the 1971-360. No problems.