I can't recall from the top of my head about the clansman stuff but the new bowman fit ambulances have a manpack radio strapped in in the space abouve the drive/commanders head with an antenna mount on the roof.
It wouldn't be beyond the realms of possability for the clansman fit to be similar but with tuams and stuff instead.
I don't recall seeing any ambies fitted with a hard mounted 351. However, to do so would require TUAAM and mounting, ARFAT and Initiate Box.
Indeed the cabling to the TUAAM mount would need to be fitted. I have seen 351s mounted in non-FFRs using this arrangement, but could not say I've seen it in an ambulance. But then you can't move for LR ambies in a Signal Regiment...
Have you tried asking on the RLC or RAMC boards?
From memory, you get several types of ambulance fit. BG's/Role 1 should have had a VHF/351 fit and those employed in roles 2 & 3 should have been HF/320. Pretty certain Role 2 & 3 fixed sites are HF and Sat