ERF-NGC-European:
Scammell couplings? Or perhaps no fifth-wheel at all! I can’t see one. R
Scammell I reckon, BMC ‘Prime Movers’ (as BMC called them) were only rated for 22 ton gtw and I can’t really remember working on any of that period with a fith wheel? However it was almost fifty years ago now so could well be wrong! 
I know the later BMC FJ 360 unit was available with a fith wheel though as we converted the braking system on some BRS contract vehicles, although the engines never lasted long enough in service to worry about stopping the things! 
Pete.