They're similar, but not identical. I don't know if they're close enough in overall design to interchange or not.
The Mustang II's subframe is based on the Pinto design, but it was altered substantially for better handling and a smoother ride compared to the Pinto, including the addition of an entire subassembly the Pinto didn't get (Ford designers called it the "Toilet Seat"). Further changes were made for the 75-78 cars since Ford decided to offer V8s.
__________________ 1976 Ford Mustang II Ghia: 302 with a 600cfm Edelbrock carb, Edelbrock Performer 289 intake, Dynomax Blackjack headers, 2.5" exhaust with Flowmaster Super 44s. RJS 11-gallon fuel cell, C4 tranny, chrome 16" pony wheels, fuzzy dice, brown vinyl half-top, and painted in the tackiest color ever (harvest gold, that's why I call it "The Goldenrod").
Also have a 2003 Dodge Ram (lightly modded daily driver/tow rig/office/dining room/home away from home/workshop... I call it "The Big Blue Dawg".) | 
Mustang II and pinto chassis 
