Is a gasket needed for the gear box?

I am changing out my clutch on my 2008 Prerunner 4 cylinder Tacoma. Before removing the transmission the gear shifter had to be removed. The way I did this was to remove to top of the gear box where the gear shifter is. When I did this I noticed a gasket. Do I need a replacement gasket or can I just use black silicone to create one?

Here is a photo of the gear box that I am referring to.

 

You will be fine using a RTV (form in place gasket). Toyota uses it on a lot of the machined surfaces anyways. Just make sure the surfaces are clean and dry. Also, too late now, but I'm fairly positive the shifter could have been removed with a simple clip under that rubber boot.

 

And just use a nice thin film like mayo on your bread thick, not a big thick bead.

 

I did see the clip but it was a bit too late. Lesson learned for next time....really appreciate the tip on just using the RTV and how much to apply.

 

I hear it's just something like Permatex Black RTV, widely available including sellers like Home Depot

 

Just clean it real well, use a plastic putty knife if needed. RTV will be just fine.

 

There's definitely a gasket used here. Whether to use RTV instead is your call, but FWIW the main cases of the transmission are sealed with RTV and not gaskets at their joints.