VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 second cross member - PG vs. standard

I know someone here has the answer so Thanks in advance. I'm restoring a 1951 Chevrolet/National Imperial Series ambulance. It used a sedan delivery as its base. It started out with a standard trans. Somewher along the way someone attempted to install so other type of large trans. To do this they cut out the center section of the second cross member. I am putting it back to the original configeration. I secured a replacement cross member but it turns out it was for a PG and is longer than the one for the standard (did not know until now that there was a difference). Can anyone tell me measurement difference between the two and also any shape differences (i got another one that the guy swore was for a '51 standard but it is wrong also. I can't seem to find any photos to see the difference. The manual only explains the location on the frame difference. Also, what should the rear mount look like? Is it the one woth the plate or the block rubberized one with the round end and seperations on top? As soon as I can get this solved I can get the rig back on the road (at least around the block anyway). Thanks

The info I have says "In the chassis frame, (with PG) the second cross member is 2 5/8" farther to the rear than it is in the conventional car. The demensions of the cross member and the braces that extend from it to the side members differ slightly...."
The trans. mount bolts to the transmission on top. The bottom of the mount had kind of a flared bracket (was part of the mount) that bolts directly to the cross member. I can't find a picture of the mount. The mount bolts to the rear bottom of the main transmission case. The 1952-54 transmission was different. The mount was farther back and bolted to the rear extension.
Hope this helps a little.

That does help somewhat. Part of the confusion was that I found a series of pictures from an old chilton manual that shows the steps for PG trans removal. In that series it has a pic of the mount that you described. But when I found a recent pic from a catalog it states that mount with the flanged plate is for a standard. Your help will be the tie breaker. Now I have two crossmembers that I secured, both being the same length and fitting the point being 2 5/8" to the rear (making them both for PG). However, one dips in the center where the mount would go while the other is straight accross with no dip. I can possibly work with one of these by manning it to fit the forward location if I know which configuration would be correct (straight or dipped). It was very hard just to find a second crossmember in the first place, then both that I bought were incorrect. For one of them I had to buy the whole frame just to get and remove it. I assumed the frame was correct since the master cylinder was still attached and it was for the standard trans. That particular crossmember is the one with the dip. If I can find another cross member I just want it to be correct this time or if I have to modify one of the two I had I want to work with the more correct of the two. Maybe I should try posting in the wanted section. And I thought that this part would be simple - LOL . Any further imput will still be appreciated. Thanks for the help and guidance

The Power Glide mount set-up was different. The actual mount was riveted to a plate that sat on the cross member. The rivets would loosen up and make noise so if the mount was ever replaced or the rivets loosened the two would be bolted together.
The 1949-51 stick mount looked more like a 1940-48 mount.....those are pictured in the various venders catalogs.
Note that the diagonal braces running from the cross member to the side rails are of different lengths also.

Thanks again. The original diagonal braces are still there and intact. I was able to drill & drift out the rivets from what was left of the cross member and save the braces so all I need is the correct crossmember . The previous guy torched the crossmember just before the braces then angleironed the trans to what was left of the crossmember on each side. I'd never seen such a buchered & half*** job like it .