Gentlemen,
I've come across an RF transistor which seems to be available in 3 very different ecapsulations. I'll use these links from Ebay for simplicity and hope they're still up by the time anyone reads this. :-)
The first case appears to be based on the TO-220 dimensionos but appears to be all plastic:
The one with the conventional TO-220 provides heat sinking adequate for a device of this power rating, but is not so good on the parasitics. Fortunately these are only used up to about 30Mhz so presumably get-away-with-able.
I don't know what to make of the all plastic encapsulation, which seems to have nothing to recommend it. Any comments? Datasheet here: