I've got a 318 67 Dodge Sweptline and a bunch of Chevy T5's. Is there a bellhousing that I can sandwich between em, or do I need an adapter? Anyone ever done this?
Unsure, but I believe that a an AX-15, or NV-3550 5-speed from a later Dodge V6/V8 would bolt right up. You might be able to get one for pretty cheap. Maybe even for the price of selling off one Chevy T5. Look for 2wd Dodge Dakota pickups. A handy yard-search site is: https://car-part.com/ A handy self-service yard search site is: https://row52.com/
You would need to drill three holes in the firewall, and one in the clutch pedal arm, and possibly extend the master cylinder push rod. Not a huge hurdle. V8 and V6 use the same bellhousing, and the Dakota came with a 318. Also, both the AX-15 and the NV-3550 used the same bellhousing, so everything is equal there, too. I drove a built Jeep with a hopped-up 4.0L for nearly 300,000 miles with an AX-15. I was not nice to it. It was fine. The NV-3550 is stronger than the AX-15, but it all all depends on what you are doing with your 318. You are in the rust belt. You might be able to find a Dakota, whole (ish), that nature has started to reclaim, and get a transmission from that, and then sell/s**** the rest.
I believe you’re correct, I asked the same question about using a newer OD manual (didn’t know the name of them) behind my LA 318. Everyone here said “no problem “.
To answer your question more directly, there are a whole lot of Mopar to Chevy adapters, but almost all of them are going the wrong way. There are a bunch of them that allow a New Venture (3550, 4500, 5600) transmission from a Dodge to be put on a Chevy. To go the other way, you would likely need an aftermarket bellhousing. Those are in the $900 range. For that, you could get a used transmission, and flywheel (pay to have it machined), new clutch, new clutch hydraulics, metal to make a crossmember, and still have plenty of money left over to take the better-half out to several nice dinners in your '67 Sweptline.
I adapted a WC T-5 to my mopar small block several years ago but sold all of the pieces and went with a Tremec TKO-600 before it was driveable. For the T-5, I used an early 70s 4-speed bell housing and then made my own adapter.