Marcel, as I look at the RFM kit, the non skid surface seems to be very understated, just like the original was. I'm not sure why Tamiya hasn't included it, other than the Tamiya kit is a straight 1969 M551. The initial tracks sent to Vietnam in '69-70 may not have had it. Those 1969 tracks also didn't have the appliqué armor either, but were given that mod in country. My track had been to Vietnam, but had been sent to rebuild and was upgraded to the M551A1 standard with the LRF. But many of our tracks were a mix of M551 (early), M551 (late) and the M551A1. During the Spring of 1978, at semi-annual tank gunnery at Wildflecken, my track had an obturator seal fail, which resulted in a blow-out in the turret--the subsequent recoil sheared the retaining bolts to the back plate of the commander's Armored cupola, which contained the battery pack for the LRF. The whole assembly sheared off (throwing me in the air), fell onto the back deck and then into the mud on the right side of the vehicle, depositing me on the rear deck. After that, the track went into the 596th Ordnance for repair. When it came back, it was without the LRF, which technically reverted it to an M551. There was a lot of this kind of stuff happening, so in the end, there were a lot of "exceptions" to the rules when it came to describing the nomenclature of a particular vehicle. I do suspect "Deathstalker" was likely a ne rebuilt M55A1/TTS vehicle, fresh from the rebuild program, so it would have had all the "new" features".
VR, Russ

In the Facebook M551 Sheridan tank in Vietnam research group a copy of instruction drawing for the instalation of the add-on belly armor has been posted. It shows that the belly escape hatch would be covered from outside (the outer of two plates having no cut-out for it) and rendered unusable afterwards. Thus Tamiya and RFM have it correct.

Yes, but the appliqué armor was removed on some rebuilt M551A1s and the TTS version. My M551A1 (Fox 36) in Germany in 1977 had the “fender” armor, but no belly armor, since the drivers escape hatch was accessible. In the photos of the TTS version at the Ft. Lewis Military Museum, (linked to the review article), there is no belly armor, and the hatch is clearly visible. So I think the appliqué armor would be found on most Vietnam tracks, but not necessarily on all Sheridans. RFM indicates it’s optional depending on the version.
VR, Russ