Going off memory, that's a newer version gear for the old TRS drive...you'll have to measure to see which block it will bolt up to...I believe the earlier ones where made in a ford and a GM version, the latter in GM only patterns.
You can use any engine that the gear will bolt up to...
As stated earlier, those gears were typically used in front of TRS outdrives...and they haven't been "popular" for a while...good news is they are tough....but finding one and someone to work on them can be a challenge...you will have to measure the gimbal housing to be certain...they are much larger than the alpha parts...