I would like to install a square drive cotterless crank on and old Raleigh Grand Prix, and I noted that that BB shell is 71mm instead of the usual 68. I know I need to use a longer spindle, so that the lock-ring will still engage the threads on the adjustable cup.
Supposedly Italian bottom bracket spindles are longer, but are expensive and only marginally longer.
I understand that old MTB bike spindles are longer – long enough to accommodate a 73mm shell.
Q - Can I assume that any junky MTB I find would have such a suitable spindle?