Hey guys,

Does anyone know the deal on the disc brake change over on 71 - 79 kombi's?

As far as I know 71 - 72 had smaller diameter calliper bolts than the the larger ones found on 72 onwards.

Please correct me if I'm wrong.

Cheers,
Ross

Yep
The '71 calipers had a different caliper bolt and were different in the disc offset/thickness.
Go to a later caliper and discs and life is easier (i.e. you can buy new calipers)

Workshop Bulletin dated October 1972.
Shows the larger brake calipers with 14mm pads (previously 10mm), with the caliper pistons lengthened 4mm (from 29 to 33mm).
It also notes the thread on the bolts securing rhe caliper to steering knuckle has been changed from M 12 x 1.5 to M 14 x 1.5. These bolts are to be tightened to 14.5 - 17.5 mkg. The fitted bolt is screwed in at the top on the new calipers (previously at the bottom).

This is also a very handy thread
http://www.thesamba.com/vw/forum/archive/index.php/o-t--t-285871--.html 

Thanks heaps bussboy vassy66T1 and Old Dubber, all the information I need.
Cheers!