After searching for more information for the gearbox (MCT-75) fitted to my 2009 +4, I found confusing informations regarding the correct oil specifications for this gearbox.

This gearbox was fitted to +4, 4/4 from (early 00's?) till replacing with Mazda MX-5 Gearbox in 2011(2012?). It is a continuation of the Ford MT/MTX-75 Gearbox used in several Ford Models from the late 80's till mid 00's as a rear drive (MT) and front drive (MTX) gearbox.

Regarding the correct oil for this Gearbox: MMC specifies 75W-90 GL4. However, Ford specified for the MT/MTX-75 Ford Spec ESD-M2C186A to pre 2000 and Ford Spec WSD-M2C200C (75W-90 GL4) for models to 2000-07/2006. Why Ford changed the specification is unknown to me. So far I understood, there were no constructive changes or new materials used comparing the MT-75 and the continued MCT-75.
Interestingly, There is a special oil still available for the MT-75 gearbox - Kroonoil SP1031. It was special development for Ford MT75 gearbox, it is even stated on the bottle (it meets the earlier Ford Spec ESD-M2C186A). Probably also similar are Lodexol MT-75, Castrol FMT?. Comparing the data sheets and viscosity indexes of both oils (SP1031 and 75W-90), it is obviously, that the SP1031 is much nearer to an ATF Oil.

Reading some Ford forums – problems witch changing gears (if 75W-90 used) during cold weather are often mentioned and cured using ATF or the mentioned Kroonoil SP1031, which was the earlier recommended oil for the MT-75 gearbox.

The MT-75 gearbox specific oils (e.g. Kroonoil SP1031) allow smoother gear changes in general and namely during cold weather. This might not be of relevance for many Morgan drivers, who do not drive their cars during winter time.
On the other hand, there are no statements how noisy the gearbox is with the particular oils, as well about the wear protection capability of both oils. In general, it probably should be more noisy with the ATF-like Oil (SP1031), as ATF has lower viscosity than an common 75W-90. This might be relevant for Morgan drivers, as they hear all the noises of their Morgans direct and unfiltered... In modern cars, more noise due to less viscous oil is not so audible, because of the good insulation.

So, not driving my Morgan in winter time (possible gear change difficulties in cold weather less relevant to me), accepting the general gear change smoothness, preferring less noise and better wear protection, I go with the MMC specification for the MCT-75 gearbox in my +4. However, the MT-75 specific oils (Kroonoil SP1031) might be an interesting alternative if the preferences differs.

Maybe some of You has more knowledge, please correct me if I am not right.

Peter