Will it work? Lower unit compatibility question

[k5blazerboy]

I have a 1988 Mercury Classic 50 (45hp) with a bad lower unit, I found this one on ebay and it looks exactly the same as mine, except where mine has a forward thrust washer, this appears to have a fixed type of washer. So just wondering if it would work, thanks guys!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=320694142113&viewitem=&sspagename=STRK%3AMEWAX%3AIT

or this:

http://greenbay.craigslist.org/boa/2294847336.html