71 Blazer 4X4 Speedometer

[71NVBlazerK5]

I have just put 33's on my blazer and now want to get the speedometer to tell me the truth. Telling the Highway Patrol, Sir my speedometer said 55 probably wont get me out of a ticket.

So the 205 transfer case has the speedo hooked to it through some adapter looking thing. HOW do I calibrate it? I know tire size and gear ratio play into it but where do I find which adapter or speedo gear I need.

Also, is there any other good sources of NOS parts other than LMC? thanks