Externally, the shifter works about the same on those as the borg warners except, I think, it is more on the top than the side.
The boat I bought had a transmission leak in the starboard transmission. I'm not sure if it was originally there or was the result of the last owner taking it apart to inspect it and replace the seals (the boat took on some water 2 owners ago, which is why it was disassembled for inspection by the next owner).
In any case, it was low the first time I saw the boat in an August. It was low again sometime later that fall (I forget when). It had allegedly be resealed sometime after that and was full at the sea trial for which I wasn't there. Neither the mechanic nor the surveyor reported any loss of fluid.
I noticed it a little low when I later took possession of the boat. After refilling it and about 3 hours of operation I noticed it low again. Low again after 3 more hours of operations. I was hopeful it was the o-ring on the shifter, which I could see was leaking a little bit. Then I finished fixing some minor fuel leaks and saw that the rest of the volume of the fluid was all from the transmission.
I chatted with the prior owner who suggested that the front and rear seals were suspects and I could replace them in-boat. I pulled the salon floor to give me better access to the engines and ran it from the lower helm for the next sea trial. I could feel it vibrate when shifting and hear excessive noise at cruise.
So I wouldn't lose boating time I had the mechanic pull it between monthly visits. He is skilled and reliable and seems to be very efficient. But, ouch, that was expensive.
His labor was about $1400. It was about 6 hours to take it out and 7.5 hours to put it in. Most of that time was just getting to it and getting it back in. The boat has a lot of constraints and I think he even ended up needing to jack (and relower) the engine. I was totally unsurprised by that chunk of the bill.
I was quite surprised that the rebuild, itself was $2564.43. I'm used to seeing rebuilds in the $800-$1200 ball park and rebuilt units selling for $1500 or so. So, it was double what I expected. But, I have a slightly weird model of the BW, a 72C-CR2. It does the counter-rotating instead of the engine. The upshot is that there were no rebuilds already rebuilt available for sale that I could find quickly. As for why the rebuild was double what I expected, I'm not sure if there is more to rebuild in that unit, or the mechanic added some margin, or he just took it to an expensive shop. But, two owners ago did warn me that the original owner had warned the owner before him that it was a weird model of transmission and to count on service being 2x as expensive. So, that part of the decades long whisper game seems to have turned out true.
The rebuilder noted that the front and rear seals on the unit were both leaking badly and that the clutches and bearings were very worn leading to the vibration and noise.
When I chatted with the mechanic about it midway through the process, he told me that the culprit was chronically running it low or without fluid, which is what I expected. I asked about the potential of an alignment problem, and he told me that that there wasn't one, but that they'd, of course, check it and adjust as necessary when installing.
So, my best estimation is that the old owner somehow got a seal messed up changing them, got it reinstalled, and didn't want to have to dig right back in and decided to run it for a while before going for round 2. And, in that time, running it low did some damage. Of course, it could have also been leaking longer than that an no one noticed, remembers now, or will fess up
A former dock neighbor also lost his forward gear en route from LA to Catalina. Fortunately, it was still in the LA harbor. He brought it back, found the fluid gone, and refilled it. He reported that it worked fine after that, put the boat up for sale shortly thereafter, and disclosed the issue to the buyer. The buyer removed the transmission himself, took it to a rebuilder in LA and had it rebuilt for $800, and put it back in himself. I suspect the seller and buyer had a different definition of "worked fine", but maybe the buyer just did it as a precaution.
Regardless, I hope your transmission is okay. But, I'm concerned. And, even if it does seem to work, I'd give it a good sea trial and see how it sounds and feels shifting and under load to make sure it doesn't vibrate, make noise, or slip. I'd hate for you to be coming in hot one windy day, shift it into reverse, and suddenly have none. Or, the opposite if you back in (and given the problem you are reporting).
If you've got the time and access, pulling them isn't too bad. And, those are usually not super expensive to rebuild -- yours should be in the $800-$1200 range, I'd guess, rather than something crazy like mine.
Fingers crossed for you!