According to data sheet pg 2 it has theta j-c of 50 deg C per watt. This is a TO39 package and theta j-c is surprisingly quite high. Look at collector pin to see if it is insulated from case. If so, it would explain the high theta j-c.
4096 datasheet and Application Note, Data Sheet, Circuit, PDF, Pinout | Datasheet Archive scroll down the page to 40965
Just for reference, a die mounted to the pedestal of a TO220 package (like LM317 regulator) has a theta j-c of 3 degs C per watt.
For a power BJT the collector is usually the die substrate. If it can be hard mounted to case then theta j-c is low. If it requires collector to be insulated from metal case then the insulating spacer drives the theta j-c up.
For RF devices, it is hard to keep stability when the entire rather large TO39 metal case is the output collector.