For sale is an Alltrax AXE4834 Programmable DC Motor Controller for Series Motors. It was taken out of a small EV that was not running so I am not certain of the condition but I believe it works. Priced low enough that you can give it a try.

The data plate reads as follows:

The controller is mounted on a board with a relay contactor, large fuse block, and some other random electronic stuff.
The contactor is a Gigavac GX14BA 350A relay with a 12 volt coil, listed on eBay for more than I am asking for the whole assembly.

Documentation and Controller Pro programming software is available from the Alltrax website at alltraxinc dot com.