Aux Tank Refurb - question

[jocko]

Anyone refurbished an old set of aux tanks? I finally got mine wrestled out of the truck today, turns out that while they still had a LITTLE gas in them, they still have about 5 lbs of dirt left in em too... Ha.. But I'm not laughing. Was hoping to refurb, but not sure how/if I can get them to the point of being able to pour in some new cleaner/sealer and roll em around before I refinish (not crazy-like, but just get rid of the crustiness) the exterior. The big issue is getting out the crud/loos dirt - and there's a lot in there evern after I tried pouring it out of the fill tube.

So, am curious if anyone has any tips on re-doing some MAJOR crud in an aux tank? Seems just about impossible to ge all the crap floating around in mine out. Any tips appreciated. Really want to save em because they are add-on wheelwell fill aux tanks and with the horrendous mileage I'll be getting, I think I'll be needing them just to make it to the gas station!