TR4/4A Gearbox maintenance

[Winston]

We put maybe 200 miles a year on 67TR4A aka (Ruby). She's been with us nearly 15 yrs. 5 yrs' ago I decided I had no idea how old the gearbox fluid was and decided it must change.
At the time I had access to a lift at my local garage. Times have changed and I don't have that luxury today. In the Haynes it say's not to drain and or overfill. I drained last time and filed with 90 wt. Hypoid gear oil. I intend to do the same without pulling the drain plug . Now............... how about two jack stands to get her at an angel, pull the fill plug and pump the oil till it spills out and return the car to level so any overfill will naturally drain.
Any thoughts?

 

[Geo Hahn]

After 5 years of service I'd go for a drain and refill rather than a top-up. It will be much easier now & next time if you make a hole in the tunnel for accessing the fill plug. I made it to accept the same size plug as the u-joint hole (on a TR4):

You can also sneak a hose into that fill hole from above but the side entrance means no need to raise the car and also the car is level for accurate filling.

If you do decide to drain & refill you might look at some prior threads to see the choices available, including synthetics such as Red Line MT90.

 

[Winston]

Thank you. I had not considered that alternative. I need to think it through for future reference.
Any technical suggestions would be appreciated.