It is a Twin Cam counterbalanced (TC-B) engine/trans from the Softail line. You can tell it's a "B" engine by the horizontal bolt hole for the front motor mount (A's are vertical). Being a TC, it's 1999 or up. I'm not sharp on the year-to-year changes to make visual confirmation to being 88/96/103, etc. size. I will pursue my book later and try to find that JBB ##### serial number. Odd to me is that it is a replacement engine, that is "used", so it must have also failed? I did find a mention that says HD did sell complete engine trans. assemblies (not as "replacement", that came with their own VIN and MSO (mfg. statement of origin) so that a motorcycle could be built and titled with said engine. The only example of an engine number was "BKLK" followed by numbers in the 90000 sequence ie, BKLK9123456. I would guess based on your photos and the stamping style that it came from the HD factory. I hope this helps you. I DID later look thru my book and added the last lines about complete engine availability.