MSD help?

[dirttracking95]

which dist. would be better to use?? I run a sbc would i want the 85501 msd or the 85571?? the 85501 has no mechanical adv. in it and is locked out from the factory, and the 85571 has mechanical adv. but can be locked! So I would guess I'd want the 85501?

[Darkstar15]

All the distuibutors we have are locked. We have one with the slip collar which comes in handy if you have a block with raised cam tunnel. The three engine builders we have had used locked dist.