Oo, can we get a pic of how you mounted that loader?
Surprisingly, Google images didnt show what a B619 looks like. I have fixed up a B670, and a couple pics of those popped up.. not sure if they are similar/same?
The B670 I fixed up on a B6100 has a subframe that engages to two brackets that bolt at the bottom rear of the tractor, and also engages part of the factory B219 subframe right underneath the pedals/floorboards. But, having cut and bent and welded and been all over it, its something that anyone who can cut and weld metal could replicate or build their own. If you fitted that LA loader to your tractor you could probably MAKE a backhoe fit as well.