Stoogecurly said:
trek bike with a 73mm bb52 thats neither a isis or squared taper its hollow....
It is probably this:
https://bike.shimano.com/en-EU/technologies/component/details/hollowtech-2.html
If so, then you just need to compare the bb's threading and width with the middrive unit you wish to use (this info would be available from the drive manufacturer (or seller, if they can be bothered), assuming the drive will replace the existing cranks and bb (this is what many of them do). If they are the same, then the system should fit there. Then the problems you may encoutner are fitting the outer diameter of the bb shell, and/or fitting up to the downtube, etc. You may wish to look at other threads using the same middrive you wish to use, with similar bike bb's.
If the middrive you wish to use does nto replace the existing cranks and bb, then it doesnt' matter what the bb type/etc is, except those that must add a chainring or freewheeling chainring to the crank spider, which means the spider must be the same bcd and type as the one to be added, and there must be space for it. To find that out you'd need to get the details from the middrive manufacturer (or seller, if they can be bothered), and match that to measurements you make with teh same method they used.
there are also several threads here about various bb's and compatiblity lists of different units to different bb's, but they are scattered around so you may have to use the google site search to find them.