The Imp could have an 8¼” - if they got the trailer towing package – but I would bet a $2 bill that it’s a 7¼”.
The body code plate might mention it, but I can’t read the picture you posted, very well (and I’m not sure what the code would be – if I could read your plate).
The C and Y-body differential housings are:
Perches are all 46” (’65 to 74), and are on bottom side.
‘65-74 flange to flange range between 56.437” to 59.437” (depending on year, SW and if Dodge, Plymouth or Chrysler), which means the axles are difference depending on flange width.
B-body perch width are 44” (’65-70)
’71-74 B-body perches are 47.3” (actually all ’71-81 B’s & R’s are 47.3”), but these are hard to find in 8¾”
A-body perches are (all) 43”
Pickups (and vans?) have perches located on top.
C, Y and newer B-body 8¾ can be cut down – but expense to do so, bites.
I would real like to get my hands on a pair of housings (even one is better than none) and axles (’65-70 (not ’65 axles though) but ’65-67 preferred) – but not really looking excited to pay for freight from there. Removing the chucks first is fine (I don’t need them).
BudW