Looks like a model 1861 Navy

The barrel contours say it's an 1851 Navy.

I agree.  The 1861 had a ratcheting loading lever not hinged like the '51.

Most cap and ball revolvers have loading levers (the exception being some pocket models that have a separate loading ram)

This is what an 1861 Colt looks like though:

And based on serial number this guy was made in 1868.

After looking at the 1851 navy, that is what it is.  It has screw placements in the same spots.  Now to determine value to see if my in-laws should fight for keeping it from the other family they don't get along with.

I'm no expert, but looking at the auction sites I'd say it's somewhere in the broad range of $1500-$6000. Getting a Colt factory letter will help its value: http://www.coltsmfg.com/CustomerServices/ArchiveServices.aspx

Cabelas just offered $385 for it.  I passed. 

Getting a quote from any big box store will just insult you.  It looks more like a "shooter" than a "collector" piece as the finish is non-existent, cylinder scroll scene appears to be all but gone, grips look rough and it appears that a repair was done to the end of the loading ram.  They are really fun guns.

Cabelas just offered $385 for it.  I passed. 

Unless it was truly FUBAR any early Colt is worth well north of $385.  It looks like a OK, commercial 1851.

They can be fixed if you want to shoot it.  Replica parts should work with a some fitting.