Hey your the guy with that on CL.
You need to correct a couple things,
1. that tractor wasn't made until '81 at earliest, not late 70's like your ad states.
2. the only way you are getting 1200# on that is if you add 50-75# wheel weights per side and then another 250-300 hanging off the back.
Those tires look to be 23x9.50x12, they will only hold 6, maybe 7 gals of fluid max. Anitfreeze is only about 9# per gallon so at 7 gals, that is 63# per side so that maybe 126# or so extra. Tractor is around 700 and blade/mount about 100. I have a 77 Sears 16 with custom winch/mount, blade , 6 gal loaded ags, 35# wheel weights, and truck rotors hanging off back and I'm only about 900 total.
Not trying to be a jerk, your ad just needs clarification.