I have a TELMA electric drive-line retarder for sale. Included is the wiring harness and dashboard controls and relay box.
This is suitable for any skoolie up to and including a 71 passenger bus, which is what I removed it from.
This is a great safety feature which will increase the longevity of your brakes X4. The safety aspect is that you can go down a hill safely and nopt really touch your regualr brakes.
www.TELMAUSA.com for details.
I may be reached at
espiritusengineering@yahoo.com