Be carefull.
You must know the gear and how the oil circuit is arranged. Some newer gears have an actual filter, spin on, installed but it is in a low pressure part of the circuit so a spin on can handle it.
Many gears run at quite high pressures and will blow a spin on apart.
Many T.D. gears run at ~ 300 lbs. or more. There is no access to a low pressure part of the circuit. The only access is the gear oil cooler circuit which is under full operating pressure.
T.D. recommends a filter that can withstand 500 psi as the gears can spike apparently.
Change the oil regularily and most gears will do just fine without a filter.
I did install one last year because I had a suitable filter, a cast off from a job, kicking around for ~ 20 yrs. and finally decided to use it. But it would have cost me over $500 if I had to go out 2 yrs ago and purchase. Then add the proper hydraulic hose and fittings.
I don't know about the B.W. units but be carefull about what you are looking at and choose carefully. Be sure you understand how your gear operates.