I still use my old yellow Boss OD-2 Turbo Overdrive, purchased used circa 1979.
Also sometimes use MI Audio Crunch Box. Little too much drive for what you want but you should check out his other effects pedals. Crunch Box was $109 new, built in New South Wales, Australia.
+1 for what juniorspecial said......try playing clean using the natural tube saturation of the amp.