Used Cars: need a 7 passenger for 6k, worse case scenario, honda odysseys

Question
Just bought a 02 Honda Odyssey because of the safety ratings and everyone I asked recommending them.  There's a shudder going from 3rd to 4th gear - maybe transmission but of course they can't find anything wrong and said they won't pay for anything anyway (was "as is").  Do I return it (for downpayment back - okd by dealer) and buy another used van (possibly with other probs) or do I stick with it and wait for possible disaster.  I just want a 7 passenger vehicle that's safe.  Someone suggested that I buy a really old one and plan on major repairs instead of keeping the newer one and not being able to afford to repair it. I have a 6k gift to pay for the vehicle and can't afford pymts.  I'm in internet info overload and need a real person's knowledgeable advice.  Please help!

Answer
Okay....first and foremost is this, The Honda Odysseys are really good vans in all areas, safety, reliability, fuel economy, they are a  real good package all rolled up into a minivan.  The transmission may be something as minor as getting it serviced, and it could be signs of a transmission on the verge of going out, you did not state how many miles it had on it so it is hard to gauge which it could be. I DEFINETLY WOULD NOT buy an older van, and plan for a bunch of repairs because of this.  Worse case scenario the transmission goes out in the odyssey and you have to replace it, you should be able to get it replaced for $3000 or under, $2000 realistically should do it.  Outside of routine maintenance, and how good the place who puts the transmission in is, more than likely that is all you will have to do to that van for a very long time.  A transmission is the weak link in any vehicle, and it does not matter who makes them. But with a new transmission, that van will run a long time with very little expense, as where an old one, will nickel and dime you for well over the $2000 to $3000 you would spend on a transmission for a really good van.  If I understood you right you are basically paying cash for this van, which means it would be free and clear.  What I would do is take to somebody a Honda dealership, or an independent mechanic who specializes in imports, and see what they think.
If they think the transmission is going out, I would probably get a refund from the dealer, and keep looking.  If they dont think so, keep the van, and know that if something happens down the road, you have a free and clear Honda Van, that you could get a small loan against to cover the repairs.  There are so many loan companies that will loan against a free and clear title, that it should not be a problem.  In a nutshell you should be able to find a Honda or Toyota Minivan that is in good shape for $6000.  Dont let miles scare you to bad if that is the case, if they have been taken care of, they will last a long, long time with little out of pocket expense.
Hope this is helpful.