A company called Emerson & Matkin makes a generator powered by a 2-71 called The Deuce.

https://www.youtube.com/watch?v=W6DuFlnIFKA

And our Nova Bus RTS buses are powered by Series 50 4 cylinder units. But I can only assume you're going after two-stroke engines. 

I have a 1978 GMC 4905 motor coach bus that has been converted to a camper. It is a "buffalo" type highway bus that shares a lot of parts with the New Look transits you mention like in Speed.  It has a Detroit Diesel 8V71, which is a non-turbo two stroke V8, about 9 liters. It's a little rough looking but runs good and we've taken it on a couple of vacations. Two stroke Detroits make a unique sound you don't hear much any more.

Matt

Indeed, you don't. We have one last two-stroke-equipped bus here still running, a 1994 Nova Bus Classic with a 6v92. It's little brother, a 1996 model, was just retired, I hear, so it's probably not long for this world. 

Unfortunately, there aren't many two-stroke Detroits in my area. When they do show up, they are usually in old construction vehicles or equipment. Propane powered buses are beginning to show up - they are very quiet.

I got to drive 4-cylinder Detroit Diesel powered baggage Tugs when I worked on the ramp out at the airport.  They were old but very reliable and did a great job. 

Once in a while I'll see an 80s or early 90s MCI highway bus still in service.  Yeah, there aren't very many RTSes with two strokes left.  There might be more in New York City.  They bought a lot of them in the mid-80s to replace New Looks that served for many years.  I was there about 10 years ago and there were a lot of brand new looking RTSes with the familiar 6V92 sound.  I heard they rebuilt a large number of those original 80s buses, even putting new body panels on them.

NYC has been putting the old buses back into service during the Christmas season. Here is an article about it. I haven't gone to see them, but maybe this year.

Since fans were mentioned earlier in this thread, I will add that I picked up two old fans. The attic at work was being cleaned out and I took a lot of metal stuff. Most of it was old broken junk that I recycled, but the fans work and just need to be cleaned up. I will add more pictures, but for now here are the pictures of a GE motor. When I first tested it I thought it seemed kind of slow, but when I removed the motor I noticed it is rated for 230 Volt - That explains why it turned slow at 120 Volt! Anyway, I cleaned and oiled the motor and it seems to run fine when wired correctly to 240V. The other fan has an Emerson Electric motor - pictures to come.