I have two old Vivitar tripods from way back in time. Built heavy and quite sturdy.
I was using one with the original "x, y, z" head but found it not the best use of the base tripod.
A few years ago I replaced one of the originals with a custom "wood" base that mounts a ball head.
The ball head is quite versatile but for panning and vertical tilt at the same time it was not the best.
When I saw the gimbal mounts it became obvious that would be very good for tracking birds etc.
However the pricing of from $200 to $700 was quite a bit more than I was willing to spend.
Simple Lathe and Mill project from aluminum and brass and a little steel.
The fun part was the 1 1/4 x 24 thread on the Vivitar pillar. It came out fine and secures the new gimbal mount.
Knobs are from Rockler. (had some left over from woodworking jigs that I made)
This gimbal mount is smaller than the commercial ones. I had one large lens that I wanted to use it with so I scaled down the commercial sizes to one that would just fit my lens and camera. It balances great at any zoon length.
The camera shoe mount and plate are from the "bay" and were not very expensive. I would guess I have about $40 in the entire affair.
Now I have my choice of standard, ball head or gimbal...Guess which one is on the tripod now!