MG Car Repair: Gearbox removal, tail shaft, mid 60s

Question
My 1980 MGB has a bad leak in the rear seal.  Is it possible to remove and reinstall the gearbox without pulling out the engine?

Answer
I seen it tried two times in different dealerships I worked in and they did do it, but both said they would never do it again as it took both of them much longer and with much hassle to do it.
I do however think I have changed the rear seal once without removing the gearbox. But if the rear bearing is bad and that is why the seal went out, I don't think you can get the tail shaft housing off without removing the box. That has always been a sore spot with all MGs, The A,B,C and Midgets.
In the dealership I pulled so many engines that I got fairly quick at it and once the rest of the mechanics in the shop wanted to know how quick I could remove an engine. I laid my tools out and had the car on jack stands. I had an engine with the gearbox on the floor in 35 min. Once myself and another mechanic did the same test on putting a clutch in a VW Beetle. We removed the engine and put a clutch in the car and had it finished and running in 12 min flat. I later met a VW mechanic who could do it alone in 15 min.
I did the MG test in the mid 60s and I used the same tools and tried it on an MG in my home shop in the mid 90s and it took me 3 hours. So it is not what you know completely, it is how fast you can move and not make mistakes.
I once put a clutch in an E-type Jag in 6 hours and the factory says it takes 16 hours. (that was also in the mid 60s)
So, if you are young and do it enough times you will get fast at it.
Good luck,
Howard