EastHill,Luker,Lamplight,Raverson
Thanks for the help.Normally,I would have assumed the PO had just put on a derailleur that matched the RD , but hadn't gotten around to finding out it wouldn't work-just the usual bump in the road you get doing projects with a mix and match parts box(room).
However,this one matches the rear derail in all respects-model/age/wear-and it matches the shifters.
Shimano DEORE LX with the shiny black finish.
Here is a much better picture of the boss.I took the side stand off.
Raverson-yes the screw is 5mm(.193"-cheap caliper) with a 8mm head.
Lamplight-I have substituted a top pull top swing 34.9 XTR derailleur,and shmmed it with a shim dohickey kit off an LX derailleur(31.8 clamp on the original derail-)I think it will work, but I never can be 100% sure until the cable is hooked up and it is working.I've tried so many things that "should work".
Luker-yes there are three slots on the top tube-just as you would expect with a top pull derailleur.
Thanks,
Charlie
PS-The old derailleur is fairly light-134 grams-less than current LX.The XTR is 109+7(shims)=116 grams