When I started in a then high end dealership in Watford in 1974, the 401 was coming close to the end of its production life and I'm sure was routinely available for £36 at discount (I need to find the old 'KJ' catalogues as some kind of proof here
). The Bastin layered plinth which the one above looks so similar to - each 'tier' individually jigged out so as not to have a 'sound-box' inside, did appear to help quieten this machine down a good bit. Prices on said bases went progressively through the roof though and no way could I afford well over a grand even for a non-veneered version - they do look quite smart in 'naked' form and just sensitively stained and/or lightly varnished and gave an excellent 'sound quality' to these decks in fairness and no bass 'boom' if the structure was thumped while playing. A Notts Analogue Spacemat (a kind of long recovery fairly dense foam) placed on top of the Garrard mat seemed to finish the 'sonics' off very well as regards record support (it remains around twenty to twenty five quid I think and I use one to this day).
I have a test UK report in a Hi-Fi Sound magazine from 1968 which measured the rumbles and grumbles from a handful of high end decks from 1969 including the 401, (Goldring) Lenco G99 and Thorens TD124 and in a well isolated SME plinth, none of them were very good but hence my comments on an earlier post, the 401's noises were very low in frequency and most likely filtered out by broadcasters (and also the much misunderstood and now maligned Quad 33 preamp which was popular at the time, with it's band limiting below 35Hz [perfect for modern small speakers which distort so much at these frequencies]).
Being an early 60's kid, I much prefer the looks of the 401 but the first one I had, as well as the G88 I owned for a few months (a few months was a lifetime when I was a late teenager) tended to 'drone' at around 100hz or so and a colleague who ran a 401/Transcriptors Fluid arm and ADC XLM told me he tried three 401's until he got a quiet one. To Frank - no idea really as you worked with them I gather, but all I can do is quote nearly fifty year old memories.