Tom - Based on your questions and other folks feedback, I did some digging in Chevy documents I can access in my own books or on line. From everything I found your 1950 3800 should have had a single mount point radiator support as you mentioned. 1st pic below is said to be an NOS GM# 3686128 3800 Regular production radiator core support (parts books show this was used on 1947-52 3/4, 1 Ton (Reg Prod) and 1953 1 Ton (Reg Prod) trucks. The single central mount point with 2 bolt holes aligned front to back match your described support mount.
If you are looking for replacement rubber cushions for this mount design,
Chev's of the 40's Part# 3684763A is a reproduction set of the correct design and dimensions that are specified for the original GM# 3684763 cushion, radiator support bracket (2-1/4" x 1-1/4").
For a little extra info in response to "2ManyTrucks" note that details are needed in GM documents for 53 to see if the mount changed, I dug a bit further. The 3rd pic below is an extract from an original 1953 Chevy Truck dealer handout that shows the front core support mount to be a single point. Kinda hard to see, but it appears to be the same as you described for your '50. Further checks of Chevy Master Parts books 1929-53, 1929-54 and 1929-57 all shows the same design for the 1947-53 under GM# 3686128 and then in 1954 the part number changed to GM# 3707013, but does not show a description or design change. In the 1929-57 parts book, it lists GM# 3707013 replaces GM# 3686128 effective 4-1-55. Leading one to believe the part hadn't changed, just the number did (something GM has regularly done) and it retroactively applied back to the 1947-53 trucks too.
What isn't addressed in this info is that the 3100 1/2 Ton and 3600 3/4 Ton trucks did have a different core support (GM# 3692219) and wide spread dual cushion mount design that differed from the 1 Ton design. Chevy even offered a conversion unit support kit (GM# 3692306) that was used to modify the earlier smaller truck mount design
from the original single center mount point to the one Kevin described above with the wide set mount holes and dual single hole pads.
NOTE: The underlined words are supposition on my part based on the info I found and read, but not specifically spelled out in any documents I could find.
I hope this is clearer than mud and that the information is useful.
EDIT: As usual Kevin posted a reply that includes some of my info in the long winded info I posted. Sorry for any duplication and Thanks Kevin!
