Well, the "fat barrels" changed over to standard size barrels in 1954, starting with Serial #112850. ( http://www.coltautos.com/
), and I've seen a .38 Super advertised for sale as:
"COLT GOVT. MOD, .38 SUPER, 5" BLUE. This early "fat barrel" was mfd. about 1952 & has correct Coltguard plastic grips with rampant horse on both sides. This is only about a 90% gun with some wear on slide and thinning finish on front strap & grip safety. Fire blued grip screws have been added. Interesting serial number is: 93333. (proper type 7 mag. is present)......$1250.00" ( http://www.harrisoncarroll.com/
If that info is correct.....since yours is an even earlier "fat barrel", I venture to guess that yours is a 3rd Model.
The Blue Book values the 3rd Model at:
100% - $1,400
98% - $875
95% - $725