@johnhull, GM lists 1975 as the start, but as with many things, I think they "rounded it off" a little. I'd say last third of 1974 on. Anything that used the 230/250/292 seems to use that date. For the first year, there was a remote coil. Then GM went to coil in cap for the sixes, just like the V-8s. If you don't have any luck with the U-PULL-IT, I'd try Skip white in TN. http://www.skipwhiteperformance.com/detail.aspx?Item=6522-R
Their distributors are made in Australia by Holden, not china like the snobs say. I have 2, one in my '69 and one in my '71 and both work perfectly, plus I've installed 3 others.

Another side note; you MUST run a new 12gauge switched wire from the ignition switch or the bulkhead plug depending on the truck.
DO NOT use the old yellow/pink/purple coil wire! It is to small and has built-in resistance. You MAY also have to upgrade your alternator to the internal style like the 10si when you change distributor.

The distributor plug, if you don't get it from the pick&pull can be had under the Accel #170072 which includes the tach lead.

I hope this all helps!

Best wishes,

Les