The RAF Brit 253 appears (from a poor copy of the aircrew manual to an unknown amendment state) to have had a nose wheel AH50916 Ref 27A/3951, with a tyre Type DC 7666T Ref 27A3975 dimpled tread, Nylon, 12 ply 32 x 8.8-16 in

I have AP1830B Chapter 2 which covers Lockheed Mk 6, 7 & 9 and in chapter 3 the Mk 8. Any use to you?

Terry

Many Thanks

TerryP

Here are some pictures of the GM7 Pilots Heading Repeater and GM7A Type as fitted to the Shackleton (and identical in external size to the G4F & G4B types) Also shown a G4B Type C with the autopilot monitor sticking out the back.

Here is a bit more of the chapter showing the Palmer valve, it does not expressly say “Lancaster” just typical installations.

Oxygen system diagram

Here is that diagram again but smaller:

I am not aware of any higher version of the basic G4 Gyro Unit. Sizes seem the same for the CL1, CL2, G4F, G4B, G4FT and CL6/SP3 versions. The G4FT Gyro Unit Type C 6B/2708 had a protrusion at the rear containing an autopilot heading error monitor pick off for the A/Pilot Mk 14 or type X23 (whatever that was!) And the CL6 Gyro Unit 6B/3750 used with an SP3 autopilot had a similar appearance pick-off.