I got a chance to get out to the shop tonight and work on the 81 again, Tonight I removed two tubs, one from the 81A thats being built, the other from a Vendo 80 parts machine. The bottom of the 81 tub is badly rotted, The 80 tub has a very clean bottom. I used a spot weld bit to drill out the existing spot welds. I will sandblast and tack weld the 80 bottom into the 81 tub. In the past I have drilled new holes in 80 tubs and converted them over to 81, in this case the 80 had a waterfountain installed at one time and it was easier to just drill out the bottom.
Bad pic but this is the spot weld bit that I used you can buy these at most automitive finish supply stores. I bought the one with the replacement teeth and it cost around $30.00. To use this you simply predrill the area with a normal bit to get a good starting point, then use the spot weld bit to drill through the actual weld itself. When finished you have a good area to weld where the old spot weld was located.
The bottom of the Vendo 80 tub.
The Vendo 81 tub after the rotten area was drilled out.
And last a pic of both bottoms top 81 bottom 80, tommorow weather allowing I will sandblast and weld the 80 bottom onto the 81 tub.
Joey