Page 58 of the on-line 'old air products' catalog has a rear air hose kit. It looks like an assortment of fittings and stuff packaged up. I would also look into using number 8 and 10 splicers to 't' off the suction and discharge lines to run to back unit. Lots of places on line have them.
http://www.achoserepair.com/fittings.html (Look for: T splicer 3 way beadlock fitting)