[Dick Linn]

If you have a fixed-wheelbase 4 wheel drive system, the delrin post works fine. There are also spring-loaded tensioners available.

If you have a simple 2 wheel drive using the drill motors and sprockets, mounting the entiire drill motor/tranny'small gear on a plate works great. You can either slot the holes in the plates or stack washers under the plate to raise it higher. I like the latter because it can't slip and you don't have to cut/file slots. It does require removing the chain to add washers unless you cut out a slot in the washers.

Use #35 chain and keep it short to minimize the need to retension. Avoid half links.