Have only had by Marelli 65amp on '97 build Defender 130 apart once. Was after I saw somewhere that rear needle roller needs regreasing regularly because it has no seal. Anyway cleaned mine and put some nulon red grease in, which seems to tolerate high temperatures. Also, found an appropriate size O ring in my box of them to put over the shaft and act as a seal. Of course like assembling many things with new O rings incorporated, they have to be checked for size, sometimes with trial assembly.
Alternators can overheat - and if excessive cook themselves due to combination of radiated heat, hot ambient air and from producing heat somewhat in proportion to the charging rate. Looking at this alternator, which I gather is a design from Joseph Lucas, appeared to me it had far less holes in the body to allow entry of air, pulled by the alternator fan on the pulley end than the common Australian made Bosch. So while it was apart, drilled several extra holes in rear casing - where they are not obstructed by something that will stop air flow. Presumably mine will now run cooler than a standard alternator in the same conditions and load. I think it is a good idea to keep the heat shield on. Have also made one for a previous vehicle I nowned.
