go to www.ford-parts.com and just go like your gona buy one and see what the shipping is. It wont telly ou the weight but it will give you an idea of price. Or...go to UPS, have them weigh it and see what they say for ground.
Have them go to their local junkyard or recycling facility and weigh it on their scale.
Freight might be the most cost effective means. UPS will likely charge an arm and a leg...and just imagine the look on some poor bastard postal worker if someone were to walk through the door carrying a tranny!!!
I shipped a 125lb A555 transaxle from a Chrysler from California to Connecticut for $62 through FedEx. IIRC, the maximum weight they will allow is 150lbs... so if the MTX-75 is under 130 or so lbs, you are good to go. Don't forget that the packaging to support it also weighs quite a bit.
To package it, I bought a big box, and used my table saw to cut some cheap particle-board to reinforce the cardboard box.. then I filled it tight with newspaper. Quite a process, but I think the packaging added up to 20 lbs. A non-reinforced box will turn to mush with that much weight pushing at it.