Our "new" "70 145 is swiftly becoming a daily driver, and since we live in Colorado Springs we stand a pretty good chance of using the seatbelts for thier intended purpose.
The 145 has non-retractable shoulder belts with the cool/funky chrome center clip, but the 33 year old webbing is getting a little frayed, and are a real trick to adjust.
My '69 142 parts car has retractable shoulder belts, but the reals are inside the door column, and it looks like the 145 wont accept them, besides they are in about the same shape.

So what belts work well in these cars, reaching way back a freind of mine put Nissan belts in his (I think) but I cant recall the specific car.
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'70 145, We
ber converson, pretty much stock other than that. & 89 740Turbo Sedan