Good Afternoon All

I'm looking to buy a Jacobs collet chuck i.e one of these:

I looks as though I'm going to import one from the USA. I've got family over there so that's doable, but I would very much like to understand the model numbers.

They seem to carry the model no 91-XY, and "XY" appears to identify the mounting arrangement. So the one I'm looking for to suit a D1-3 camlock seems to be a model 91-C3 (C for camlock, 3 for size). So far so good.

I found a user manual on the net, but it doesn't seem to show how to decode the model suffix, and whether I've reverse engineered this correctly. But it does seem to show that an A suffix chuck (flange mounted) can be bolted to a backplate – which then could carry a D1-3 camlock. Or am I making this over-complicated? An L suffix chuck seems to be suitable for the L type Amercan keyed taper, but the mounting seems to be an integral part of the chuck and wouldn't be sensible to adapt.

There is also this one just come up for sale on ebay part no 91-66. What's one of those? Is this maybe a typo for a 91-C6 which would – I think – be a D1-6 Camlock mounted unit?

Has anyone got experience of the innards of these and a digest of the model numbering system?

Looking forward to your help and advice, thanks in anticipation, best regards Simon