looking for part number 16520-74020

Hi I have a 1992 Toyota MR2 Turbo that I am trying to rebuild. I have it almost completed, but I am still looking for some parts and one of the is the coolant filler assembly. The part number is 16520-74020. I have looked everywhere for this part, and it always comes up discontinued. If there is anyone out there that can help me with this Please let me know. 
 
Thanks

Tony, 
Thank you so much for your answer, but could you please tell me what tcs is, or where it is that I could find it. Also what is the straight filler neck and will it fit my car? I really do appreciate your help.
 
Thanks.

Many things for the mr2 are discontinued (meaning need to find second hand) or an out dated design and better components available.

Due to demand by the mr2 community there are many upgrade parts available. The filler neck, as example, (quick grab from google)

https://www.tcsmotorsport...motorsports-water-neck

I believe they do one that deletes the part you are looking for, reduces failure points, looks bling, and will set you back about $300+ aussie delivered,

TonyMR2
Thank you for all of your help. I will be looking on that webpage to see what I could do. Please and if I have more questions I sure hope that you will help. Thank you so much.

Great please let me know.