Mike, there's a bit of confusion that runs over this sort of thing because of the FAA's practice of assigning year manufactured ... as the same year it's airworthiness was issued.
Cessna made airplane model changes similar to the same method used by car mfr's. In the fall of the year, the next year's models are rolled out and sold to the public. The day the factory applied for the first airworthiness certificate is the day and YEAR model that the FAA designates the aircraft....regardless of the model features the airframe actually has. In many cases aircraft are registered as a year model EARLIER than they actually are. (Cessna may have applied for airworthiness certs in groups, and your airplane may have had it's application made before others of lower serials for lots of reasons, such as installed equipment availability of other airplanes, paint, etc. etc.)
An example is my own 1953 B model. It's a '53 model by virtue of it's serial number and features of pressure-cooling cowl, improved cabin heat system, etc. But it came off the assy line in Nov '52 and the FAA thinks it's a 52 model and various paperwork associated with it call it either a 52 OR a 53. It's definitely a 53. It even has the LATE 53 gear legs installed on post sn 25612 aircraft, as my sn is 25713. Heck, for awhile, the FAA called it a 1970 model! ... because it actually never got it's first airworthiness cert until after it was re-imported in 1970. It took an act of congress to get them to realize the error and change the records...and THEN they called it a 52!
The 1949 A model had the same lower cowl opening as the earlier ragwing, while the 1950 A model has the same lower cowl opening as the later aircraft. If your cowl hasn't been changed out, that may help you discover your answer. But I'd guess it's actually a 1950 model. In fact, a lot of the aircraft registered with the FAA as 49 models are probably 50 models simply because their airworthiness certs were issued before the year's end.
Changing your paperwork probably isn't worth the effort, in any case. The FAA will resist it like pulling toe-nails out, and your insurance company will go by serial number anyway, and probably won't care.
If it's still important to you, you could always contact Cessna Publications and they'd pull out the microfiche and send you a copy of your aircraft's original application and equipment list and copy of the test flight records, for a fee. The equipment/specification sheet would give you all the info you seek.
The 170 Book also lists serial numbers by year. (Available from
headquarters@cessna170.org I don't have my copy with me.)
(I officially joined the Old F---s club this past Sunday).