if that's your original crankshaft pulley/harmonic balancer, it's probably a good idea to do it during your timing belt change. The HB probably won't last till the next timing belt change and since you have all parts disassembled for it anyways, it's probably a good idea to do it now.

I purchased my ScanTech HB from FCP Groton back in Nov 2002 for $65+6 for shipping (no sales tax). Took them about week and a half or so to get it out to CA. Not bad considering it's shipped UPS ground from CT. FCP Groton is the cheapest place I've found for mechanical parts. You could try junk yards, but I wouldn't recommend it for this item.

I compared the ScanTech to the original Volvo when I had it off and the overall quality is comparable. The only precision involved in this part is the knotch for mating it to the crankshaft and the accuracy of the timing mark relativly to this knotch.

So far, I've put on 10k on my 88 740GLE (B230F) since the HB change. I haven't had any problems yet; and NO that's not knock on wood because my two (91 940 GLE) Volvo's are more reliable than my 2000 Ford Expoder.

Good luck on the timing belt,
Chris

BTW: the counterhold tool is a godsend. I borrowed one last time from a friend of a friend. Where did you get the 5284 and how much was it?

Yes, replace it: it is due. The ScanTech unit is OK, but has rounded cutouts that slip when you use the 5284. I prefer the OEM unit,more expensive but better-formed. Get it from a discount dealer such as Borton's.