I have a part i need to quote but i have only done a few worm gears and i was hoping some one could help me out

the gear is

1.500 pitch dia. 6.667 DP
single thd right hand
20 degree press angle
5 degree 43' min lead angle
& .4712 lead

One thing i need to figure out is the major
well actually i need to figure it all out i think i know part off it but a little unclear

I hope this helps. According to "Gear Design Simplified" For lead angles less than 15 or 20 degrees, the addendum equals axial pitch multiplied by 0.3183.

Check my math !!!!!! .4712" lead X 0.3183 = 0.14998296 X 2 = 0.29996592
1.500" PD + .300" addendums = 1.800" od (I think)
Dick Z