[GMCNUT]

Originally Posted by AZKen

The "overflow condenser" shown by Groby and others was definitely an accessory in the 50's and earlier. It was used on vehicles without A/C. It was used in vehicles without special radiators. Just guys adding a neat aftermarket gizmo they didn't need.
If they are "Factory", GMC would have mounted them in exactly the same place with exactly the same bracketry, hoses and hardware; and be the same unit with GMC logo. The fact that they are on A/C truck with larger radiators just means that GMC could have used larger radiators with A/C. Does not mean that the "overflow condenser" was installed at factory. The overflow condenser does not keep the radiator from over heating due to more "heat and strain" anyway. If they used a bigger radiator so that it would handle the A/C "strain", it would handle it.
The examples I see so far on this post show that the units were not mounted the same. They look aftermarket/dealer units.
If the vendors thought it was used in 60-66 they would surely include those years for more sales.
Until it is found on a build sheet or in a GMC document for 60-66, it should not be labeled "Factory", that's my take on it. Just an opinion not hostility.

Ken / Jon - the GMC factory installed radiator overflow tanks on AC trucks have a special bracket made to fit a very specific spot on the right inner fender behind the battery - in 100% of the cases I have observed including all THREE tanks I pulled and saved here, they were mounted in exactly the same spot. I know you guys don't like to believe the books are ever wrong but they are sometimes wrong I hate to tell you. Jon's 1964 Chevrolet Data book does not show a 327 V8 option for 64 1 ton C30 trucks, but somehow magically he now has one with that very motor and with assembly line installed AC no less - something else hundreds of book believers didn't think could happen. Jon's C30 has all the ppwk showing the 327 and shows assembly-line AC both being ordered for it - so look guys - we can beat a dead horse a thousand times over trivial stuff, but I am telling you from EXPERIENCE - these 65-66 GMC AC trucks have Radiator overflow tanks on them that have been there from day 1 regardless of what the books all say or what the books omitted. The only book any of you can count on is the Bible - other than that, they are often as flawed as those who wrote them.