LMP: Which blower motor for my 1990?

I went to buy that new blower motor for the van, but the guy said there are two kinds. A press on and a bolt on. He said I'd have to take off that housing to see which one it is. Do you by any chance know which one I should buy?
Thanks again,
Mike

Negative. Sometimes they switch those non critical parts type in same year, or run 2 suppliers altogether. However, the exactly same question came in 6-8 weeks ago and my suggestion was to get a used motor AND impeller unit at the scrapward and then it did not matter if it was similar or not, it would fit right in anyway.
http://www.automotiveforums.com/vbulletin/showthread.php?t=372918

Otherwise, if you want to implement the brand new motor option, you should take the blower unit out first to have a look.

Either one will work. Used they go for $30, new for about $60.
There are many other vehicles that use that blower. If you go used and pull it yourself from a junkyard, pull it out of a bonneville, its easier to reach.