my vehicle has the factory fitted power steering, and it has the same diameter sleeves on the l/h side as well as the r/h side.
Is this correct for my vehicle or should one size be a much larger diameter than the other?
He's correct, the left side is larger and uses different clamps and bolts, 379179-S2. That bolt has a square "shoulder" at the head (it's still a hex head bolt) and it's a 3/8-24X1 5/8 inch long, grade 5. The nut is special too, 372755-S(
3/8-24 cone locking.
All the above hardware is documented in the Library section of this forum under "Mustang Hardware Spreadsheet 64-66". You will find two spreadsheet, one by part number, the other by application, aka location/application. Under the application scan down to "Tie Rod - - " for further info. The source is the 75 Ford Car parts, MPC, SEC 030 P18,ILL 036 P04, 05, 06. As far as I can tell, the bolt is not reproduced and is only available from salvage yards.