looking to buy..

Looking at buying a 92 lsi from friend of a friend. Has 150,000 miles,been in the same family since new. Recent ecm and alternator replacemant. After visiting this sight for last couple of days,I need to find out if Trans has ever been replaced/rebuilt. I'd
call its condition as above average for miles. Few door dings,scratches but no rust. One other person has first dibs on it,but if they fall through,and I think they will,I can get it for $1500.00. Any feedback would be appreciated. I also have a Miata and spend time on that sight. Thanks.
P.S what kind of synthetic fluid for trans is o.k. and does it mix with standard fluid?