I really don't know what I am talking about (as usual) so bear that in mind.

However, our Angola had a retarder which was almost useless. That bus just did NOT want to stop. Witness the knuckle-marks on the steering column and my footprint on the brake pedal!

The Vogue had a Jake Brake on it and it sounded kinda cool (now we are Series 60 land), but I didn't see any big difference in stopping power with it.

Our new camper has kind of a neat deal. On the right hand side of the steering column there is a lever with a 4-position adjustable retarder. I was goofing around with it the last few days and as the tranny downshifts and you change the range of effect on the retarder, you slow down mighty quick.

I wasn't looking at the temperatures as I try to watch the road, mostly.

So that's my 2 cents worth.