[60-66]

In am effort to help set the record straight on factory floor mats. I've researched many original trucks and parts books and compiled a part number list. ALL Chevrolet and GMC original matts will have a 7 digit part number only molded into the mat. The 8 digit numbers I've seen listed in this thread are aftermarket floor matts. Many aftermarket companies copied or supplied GM with their matts. I have several mats in aftermarket boxes, the GM part numbers are readable but before they went in these boxes the part numbers were ground off or partially ground off.

1960 Chevy trucks had a one year only pattern but was used in 1960 and 1961 "N Series" GMCs Part number 3773705 for Hi Hump and 3766883 low hump.
1961 The matts received the same pattern used through 1966 but differed in the cut for the different 60-62 floor humps although some of these numbers cross from 1962 to 1963. I tried my best to find numbers that were actually used in each year truck rather than what " would fit" or interchange to a given truck. The parts book lists 1961-1962 mats as the "Second Design for 1960. That does not mean trucks produced in 1960 got a 1961 mat , simply it was a "replacement" .
1961 1962 low hump is 3782307
1961 1962 Hi Hump is 3778943
1963 1964 Hi Hump 3822803
1962 1963 Low hump is 3822765
1964 1965 early low hump 3838981
1965 1966 low hump 3865525
1965 1966 Hi hump 3865527

Through at least 1963 GMCs used Chevy mats. Somewhere around 1963-1964 GMC went to its own floor mat and GMC part numbers because of the fawn painted mat.
GMCs are still a bit of a mystery as far as reading and totally understanding the language of the parts book .
I've confirmed these numbers as :

1965 1966 Hi Hump 2440066 GMC
1965 1966 Low hump 2475935 GMC

If you have a 1960-1966 Chevy or GMC with a different part number mat and your certain its original to the truck please let me know. There's a bunch of other numbers but these that I've listed fit our 10-30 series trucks. Some could be different for a hand brake or 4x4 .

One thing these all have in common is, they all have one of these part numbers molded into them on the edge closest to the seat.