Sorry, I was talking about Moss or Jaguar made to Moss design gearboxes as used on XKs and 3.8 E-types.
Your question is regards all-synchro E-type Gearboxes.
The prefix letters tell you.
EJxxxx is Close Ratio with gear helix angle greater, and was later considered a little noisy (not in an OTS where you couldn’t hear, but more so in a FHC
EJSxxxx is same Close Ratio gearbox, with an extension for 2+2 only.
EExxxx was next, now a wider ratio gearbox, still with same noisy helix angle. Only found briefly with Series 1-1/2
KExxxx for all Series 2 OTS and FHC was next, still same wider ratio gearbox, but with finer helix angle for quieter running, but at expense of less efficiency, so some loss of transmitted power. These are normal
KJSxxxx is normal for Series 2 2+2, if not fitted with Automatic.
So your EJSxxxx is a Series 1 2+2 close ratio gearbox; there was no CR suffix clues.