ERF-NGC-European:
I was driving Mercs during the changeover period. The last of the NGs was the 1633 IIRC and that remains, for me, the last good Merc. It had the awful ZF Ecosplit knock-thru’ (but far better than EPS!) but was reliable and went like stink. The 2035 I drove had the NG cab but was basically an early SK, complete with bollox EPS. I was told at the time that Merc would not supply a manual option for love nor money. Only the rigid SKs I drove, as CF rightly pointed out, continued to have the ZF manual.
I later drove early Actroses with the Telligent 'box, which were just as dreadful. The only SK I actually quite enjoyed was a trip to Morocco in the big high-cabbed version of the 1850 and that was a proper uphill-downhill machine in the Spanish mountains! Robert
I guess that the Ryder 1628 unit I drove was probably an E reg so probably similar on the point of changeover from NG to SK although I totally missed the distinction.But like the later rigid ‘Powerliner’ was deffo a manual option.
I think the later 16 speed manual option used in the SK was an in house Merc box,as opposed to ZF in the NG ?.The shift quality being worse in the case of the latter if that’s possible.On that note I think the move to EPS was probably thought by Mercs management as being more by necessity than design because the Merc synchro manual boxes and/or their installation were just so bleedin bad to use.Especially when compared to DAF 85/95.Although like you I still preferred to put up with that than being lumbered with the,at best,stupid slow witted EPS lash up.Which I only ever drove once on a driving assessment for an international job and told the interviewer what I thought of it 
.To his seeming agreement and I got the job but which then fell through before I started I’m guessing because of typical elitist pecking order politics.With hindsight maybe a lucky break because I soon would have got fed up with driving around Europe with something with a box full of neutrals. 