Hi BDA & Lotsof,
The 365 is a 5 speed, Renault product. The only mod that Lotus did was to swap out the 5th gear, made by Hewland and so marked, and syncro/drum to match such that it would be an 'overdrive' rather than a sequential ratio. The normal, French, 365 variant had a 0.93 fifth gear ratio. This mod, I think, was to satisfy Federal requests for fuel savings, and help with marketing. It was during the 'fuel crisis' after all....lol
The rear case can be manipulated off with the trans in place, well, kind of in place since you have to lower it all to clear the rear hoop. IIRC, you remove the upper two motor mount bolts, and loosen the lower ones, and you may have to remove the lower radiator hose to permit enough rotation to clear the rear hoop. Be aware of any other items that may restrict movement, like the upper radiator hose, wiring, etc. One must be very cautious however, when doing this or you will be disassembling the whole box. There is a ball bearing which acts as a detent for 5th gear which can fall into the forward case if you do not select 4th gear, and keep it selected, as you remove the case. Instructions are in the manual for more detail. The shifter shaft has to be manipulated during this process also, so the case is permitted to move aft. It is a tedious task, and now in hindsight, I remove the whole transmission if I need access. If the rear case is removed, make sure you replace the shift rod bush, and seal since they are a high wear item. If the crack is minor, by all means weld it, but be cautious of any warping and coat the weld on the inside with a sealer to prevent the weld from weeping trans oil. Any warping of the case can cause misalignment of the shift rods, not to mention gasket leakage.
Good luck,
Jerry Rude
4005R