What do the instructions say about the Ranger, do they recommend an extra transmission mount in your application?

It's possible too that adding another mount may overly constrain the engine and transmission to the flexible frame, then causing vibrations at best or broken mounts and bell housing at worst.
If more support is necessary design the new mount such that it carries the weight but does not influence location. A factory example is Roadranger transmissions are long and very heavy, the 10 speeds don't usually have extra support, but the 13 and 18 speeds may. They commonly use a leaf spring transverse to the frame to share the weight. Here's a picture

I've seen and heard of these troubles with vibration and broken stuff in diesel conversions where the well meaning installer adds more mounts for the "bigger and longer" drivetrain without understanding that the engine and transmissions are stiff, and the frame flexes.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-