I am in the need for a v belt tensioner that I can adapt off an a/c bracket. I have spent about an hour on line looking for something I can fab up but almost all the tensioners are for flat serpentine belts and the few v belt tensioner I saw look like machinery applications not automotive. Any suggestions welcome.
Many late 60's though the end of V belt Ford V8 engines had them. Start with a search for 72 Ford AC idler pulley and go from there.
Look foreign vehicles.. Nissan pick ups Honda CRV/civic they had V belts with adjustable tensioners mostly for the A/C Here is a OT bracket ass. a bit pricey if you ask me you can get the idea 327892 Roller Tensioner For NISSAN Navara Pick-Up (D40M) | eBay It is a later model but early ones had V belts
And as Mr48chev stated Fords with the YORK compressor had the idler on the bracket. ford FE with ac - Bing images
Top center in the photo Jnkyarddog_1 posted, should be the same as 69 mustang 5.8 a/c idler. Rock auto has them for around $15.
All the old add on air conditioners with the York compressors seemed to have belt tensioners. If you find an old one, it takes the same bearing as most old alternators.
Use a V-groove for pulling the belt out but a flat tensioner can be used on the back of the belt for tension, too. Using a flat one on the back can be better because it increases the belt contact with the pulleys on both sides where a v pulley decreases the contact.
Consider a mid 90's GM tensioner, here's the back. Easy to mount and uses a pin to locate, clock it anyway you need. Easily replacement, and many lengths and offsets, GM used them on everything Can use it in the back of the pulley, as onetrickpony suggested. If you want to swap the pulley, get one with a sealed bearing. Bearing will have a number in the seal and can be replaced if needed, pulley shouldn't wear. I searched for 3" diameter steel v pulley, need to ensure the bearing bore aligns with the bolt for the tensioner.