The problem is that this is a Type IIi (which some people will tell you doesn't exist; it's actually a Type I with some Type II IDs) system, so block sizes will not be correct.
I don't know how Radio Shack scanners work in terms of trunking. It sounds like it is expecting Type II IDs (which are in multiples of 16, as far as the "decimal" notation like 30736 goes). 30736 divided by 16 is 1921. That's a valid Type II group. 30739, however, is 1921.1875 - which is an "uneven" number and is invalid as Type II. (If it
was Type II, it would be 30736+3 which is "talkgroup patch to another" as per the
Status Bits page on the wiki.) Since we are reasonably certain it's not a talkgroup patch, and more importantly, the voice on 30739 is usually the
same person or same unit identified, this must be a Type I talkgroup.
But which Type I talkgroup?
Again referring to the wiki, there's a
fairly decent explanation on how to determine which are which.
What I do for the time being, until I figure out the right Type I ID, is leave this system in Type II mode with Status Bit set to ON, and let it show me all the IDs that might match that particular fleet/group.