[GreenKeys] the meaning of M28 model numbers?

[Nick England]

Hi gang - where within the wonderful world of Teletype Corp.
publications can you find out what an LPR6ARJ actually is?
OK, LPR means it is a M28 typing reperf and I found an LPR parts book
that says ARJ is the typewheel configuration. But what's the diff
between, say, an LPR6 and an LPR5?

The LPR parts book has a page for the 2-shaft frame and for the
1-shaft frame - but surely there oughta be a chart that tells you what
models have 2 shafts and what ones have 1 shaft, etc. The LPR
description and theory book doesn't help.

My 28ASR came with an LP6ARJ - what publication tells me what model
LPR is supposed to be in a 28ASR?

I gotta believe that some publication somewhere must tell me that an
LPR6 is used for the 28ASR keyboard reperf and an LPR37 or whatever is
used for the 28ASR dome reperf. Inquiring minds want to know!
thanks,
Nick, wandering in the TTY desert.