A good option for your retro Old School Bike Build is these Redline 3pc BMX Cranks. These Redline cranks are 175 mm long and chrome.
If you're looking to design a BMX Racing Bike retro, then these Redline Flight Cranks are a great option. Redline cranks mount quite readily once you are pushed into your frame with the cups and bearings.
The arms of flight just slip on to the axle of flight. 48 Spline cranks such as Profile Racing involve an instrument for pulling the crank arms on or off the axle. Once they are pulled on and off a few times, profile crank arms will become simpler to push on and off. Profile Cranks are produced in the United States and involve more mechanical skill than Redlines to install.
Redline Flight First Generation 3-Piece Crank Arms with Original 46T Redline Sprocket. No Hardware Included.