MK5 front seat construction compared to 1946 Mk4

Hello Gents, a question for anyone that has restored a MK5 seat…

One of the front seats in my 1946 Mk4 is unusable due to water damage and it is unsafe (extremely corroded). It was suggested that I fit MK5 seats instead and I now have a matching pair of frames so I am looking at the physical differences and how to trim them to look like a MK4 seat.

The MK4 seat seems to be 1.5" narrower at its widest part and has a spring pack in the back support upright. The MK5 seat has a noticeably thinner seat cushion spring pack and very obviously 2 side of the back supports. Looking at photos those back side supports are trimmed separately compared to a ‘single piece of leather trim’ in the MK4.

Does the MK5 seat back also a spring pack?
I am asking because I am considering trimming the MK5 seats to look period correct.

MK4 seat
MK5 Seat


Here is a photograph of the seat springs in a front seat of my Mark V parts car. Both the seat bottom and seat back have spring assemblies. Seat back is on the left in the photo, seat bottom is rotated to vertical in the right of the photo with both seats detached from the floor.

Perfect - thank you Roger. I will use my mk4 seat back frame as a template then.