Volvo - Technical service literature update No. 25 Issue date: 6/92
Timing gear belt, B6304F Replacement interval changed to every 20,000 miles.
Starting at 20,000 miles the new schedule is 20,000, 40,000, 60,000, etc.

If you own this car, you need to make absolutely sure that all TSBs with respect to the timing belt, the tensioner pulley, and the entire mechanism have been implemented. The 92 engine suffered from abnormally low belt life and Volvo made several improvements, which have to be installed on the engine, to deal with this. If you ignore these, you risk ruining your engine.

I guess it's possible that these TSBs have not been addressed, especially if the car had not been serviced at a dealer. The damper was to be installed at the 40K interval (at least that's how it was noted with my car). My owner's manual had a notice actually inserted in the pages that told of the procedure, that it was to be paid by Volvo and that it would increase the interval to 30K.
See: http://www.brickboard.com/FAQ/700-900/EngineSealsBeltsVent.htm#960TimingBeltChange
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John Shatzer, '97 V90 @ 105K

This technical bulletin predates the modifications made to the timing belt balance, changing the interval from 20k to 30K on 92-93 model years. Not sure about 94 because at some point they also increased the width of the belt in those 'transitional' years until it ended up at 70K for late models.
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John Shatzer, '97 V90 @ 105K

Wonder how much the dealer makes for changing your timing belt every year or so?

It's the shortest change interval I've ever seen for any make of car.

These are very easy to change yourself because of the two piece timing cover. You no longer need to remove the crank shaft pulley to get the timing cover off as with the 740 and 940 models.