Honest, I was framed.............. The following info will show you how to identify a 442 by simply looking at the frame. There are several differences which are easy to spot, if you know where to look.  This is about the only definative way to verify a Fremont 442.  ( Note: there are 4 different frames in 65  442 / non 442 / 442 convertible / convertible )

This frame page compares the basic F-85 frame and the gusseted frame that came standard on the 65 442 Standard, Sport and Holiday Coupes.     The special order boxed frame ( order code F-35 ), which is not yet pictured on the page and was rarely seen on a regular 442, is the same as the convertible.      The overwhelming majority of 442 frames were the re-enforced / gesseted type. I have never come across the boxed type, except under the convertibles.
3.  The "Frame Stamping" on the left rear of the frame, just forward ot the tailpipe hanger holes, is unique to the 442. This number is the same for both Lansing and Fremont built 442s.  The following pictures show the location and examples from both Lansing and Fremont built cars. Coupes  3864503  S   Convertibles 9780503  S . The number above varies.   You may have to lightly sand the paint and / or rust to reveal the number stamping.

Note: The convertible frame is very similar in appearance to the heavy duty 442, but the rear frame number  is ......      9777400  S   on regular convertibles and  9780503  S  on the the heavy duty 442 and convertible 442 frames.
1. The 442's side rail is a continuous sweep up and over the rear axel housing, where the "non 442s are welded just before it starts up and over the axel. This is very easy to spot and you don't even have to get your knees dirty.
2. The rear spring perch cross member on the 442 is totally different from the non 442s.   Notice the cross member on the 442 optioned cars (left) has a lip in the center (for no apparent reason) and the regular F-85 Cutlass, Club Coupe & Sport Coupes (right) do not.
4.  A true 442 has 4 holes where the rear-end upper control arm bolts to the frame (note: 10 bolt rears are in the 3rd hole from the top, 12 bolts are in the 2nd), the "non 442s" only have 1 hole.  You can see the difference in the pictures below.  This can't be counterfited without cutting and welding connecting points to  the frame or trying to accurately drill the other holes. ( The top & bottom holes were non-functional, since there were none on the opposite side that matched up with them.
5.  As you can see from the pictures below the 442 frame has extra support (gussets) behind both sides of the front cross member.  The second picture shows one of the gussets being replaced.  It was removed at some point in time for header clearance.
This picture shows the location of the stamping.
 This frame serial number was found much futher back on the drivers side rail.

Convertible 442 Frame Numbers