Funtronics nor soda jerk works sells one specifically for the Vendo 56..but this one pictured might work if the measurements are right.. but I measured it and ended up making one out of a block of wood... it does not have to be round, just the hole has to be large enough for the vend shaft to go through.. I think it was 5/8.
if I recall it's only 1 1/2 inches deep..
Thanks th one from SJW is as follows; 1.5 L - od 1-7/16 – id 1/2"