I schnipped the following from
http://www.oldvolkshome.com/ignition.htm
These are the stock SVDA (single vacuum, dual advance) distributors. You can also get a range of aftermarket models.
Bus & Pickup Late 1976-1978 All States, 1979 Federal * 2000
Note: This Distributor also fits Type 4 (412) 1974
Distributor: VW 021-905-205P, Bosch 0231 168 005 > 022-905-205S, 0231 170 093
Note: 0231 170 093 dist primarily used on California Late 1976-1978 and all Federal 1979 Models
Can Use:
Points: 01 011
Condensor: 02 074
Rotor: 04 033
Note: 0231 168 005 dist originally equipped with Speed Limiting Rotor 04 016 (5400rpm)
Dust Cover: 039-905-241, Bosch 1230 500 139 > 1230 500 147
Cap: 03 010
Distributor Cap Clip: 034-905-265, Bosch 1231 251 033
Parts Kit (Shims, Washers & Hardware): 059-998-211, Bosch 1237 010 007
Coil: 00 012
Vacuum Can: 07 060
Ignition Wires: 09 171
Spark Plug: W8CC
Timing Set At:: 7.5deg BTDC @ 850-950 rpm (Man Trans), 900-1000 rpm (Auto Trans) w/strobe, vacuum hose connected
Advance/Retard Range: Vacuum: 8.5-11deg Adv @ 7.9 In. Hg; Centrifugal: 8-13deg @ 1600 rpm, 20.5-24.5 @ 3400 rpm