I love seeing old trucks like this in original "time capsule" condition..
It is so rare now to find an unmolested one..
I had a '71 GMC with a 8 foot fleetside bed and it had a wooden floor--but I cant swear the bad was original..I think GM had wood bed floors available up till 1972..(StepSide beds had them much longer,my '82 GMC has an 8 foot wooden floored StepSide bed)..
Years ago I had a 1972 Chevelle "Nomad" Wagon on a '69 K10 Suburban chassis that had the Rockwell transfer case..everyone thought it had a blower on it,the gear whine they made sounds almost the same..should have kept that car,it had a 454 I put in it and with the divorced Rockwell T-case ,it would have been easy to put any automatic or manual transmission in it..
That steel pipe on the upper radiator hose is factory,I had three trucks that still had them ,the 71 GMC,a '72 K5 and a '71 K5--and I have a NOS pipe still hanging around I found in the cab of a junked C-10 at the salvage yard years ago--still had the sticker on it!--I used it for a short time,then found out a upper hose from a '71 Monte-Carlo fits perfectly on the 67-72 series V8 trucks..