Curtis,
The answer to your question all depends upon whether you have a gear drive
B7100 or a hydrostat
B7100. I can't remember when Kubota started making the hydrostat
B7100, but it was around 1983.
GEAR DRIVE:
(1) The mid-mower for the gear drive
B7100 was a 48" belt drive model that operated off of a front PTO (a pulley & shaft assembly running off of the front of the crankshaft with an automotive A/C compressor style clutch assembly to electrically turn the mower on and off).
(2) The gear drive
B7100 did not have a mid-PTO (at least mine doesn't).
(3) The gear drive
B7100 did not have a "live" rear PTO, which makes rear mowing a real pain, unless mowing wide open spaces.
(4) This mid-mower cannot be purchased new anymore. Parts are available. You might be able to find a complete unit used.
(5) This mower is a real PAIN to remove an install.
HYDROSTAT:
(1) The
B7100 HSD/ HSE use a mid-PTO to drive the mid-mower. There were 54" and a 60" mid mowers available for this tractor.
(2) New mid-mowers may still be available, and I've seen several used ones for sale.
(3) These mower are easier to remove and install relative to the belt driven mowers.
(4) The
B7100 Hydrostat essentially has a live PTO, which makes 3-point mower much more convenient to use.
Rear mowers are generally much cheaper than mid-mowers since mid-mowers are usually custom built for one specific tractor model and rear-mowers are more generic.
Hope this helps. I'm sure that this response will generate more questions.
Kelvin