A two pickup version of the 4000 bass at the time, featured horseshoe bridge pickup, toaster neck pickup, full width triangle "shark fin" inlays made of a pearlescent material, and checkered binding. 1962
Early 1962 The tailpiece is replaced by an aluminum cast which features a built-in mute. We do not have a photo of a 4001 from the year 1962 unfortunately.
The pickguard shape turns into the more traditional and recognized L-shape that we know today 
Crushed pearl inlays replaced the previously used pearlescent material. 1968
"Made in USA" verbiage moved from being parallel with the Rickenbacker logo to being parallel with the nut. The truss rod cover design also changes to incorporate the model number (4001).Second half of 1968 
Rick-O-Sound became available on 4001 bass guitars during the second half of 1968
Horseshoe pickup replaced by a "hi gain" pickup. It features a plastic chrome pickup cover to carry on the tradition of the look, though the chrome pickup cover can be removed without having any impact to the sound, as it is purely aesthetic. 1969
April 
The pickguard shape changes and becomes shorter
Photo credit: Ron O'Keefe
September-October 
The headstock shape becomes shorter
Photo credit: Ron O'Keefe
The "skunk stripe" introduced as a strip of shedua is sandwiched between maple to effectively make a stronger neck. The walnut headstock wings at the same time were replaced with maple. 
The "tug bar" disappears 
Full width inlays no longer crushed pearl and become acrylic 
The inlays changed again, this time inset (not full width) and now a poured resin material 
The "Gap tooth" cast aluminum tailpiece replaced by a zinc tailpiece held on by 5 screws rather than 2 
Checkered binding replaced by solid white binding 
Toaster pickup neck replaced by a "hi gain" pickup 
The neck pickup position moved 1/2" away from the fretboard which as of 2025, has not changed since for both 4001 and 4003 models. 
January - The truss rod cover transitioned from being a white back-painted plexi cover to a raised letter injection molded truss rod cover. 1985 - Last known production year
November Since early 1976, there were very few changes, likely because the 4003 was introduced in 1979 and became the focus as the 4003 eventually replaced the 4001. The last known standard production 4001 is documented as being built in 1985.
