420A Transmission issues

[me2151]

I have a 95 eclipse GS with a "4" speed transmission. I say 4 speed because 5th gear doesnt do anything.
The issue is when driving 1-2-3-4 all work perfectly and even reverse engages. 5th gear feels like it engages but it acts like its still in neutral. The shifter is in the 5th position but no drivability. Now if I,while driving, try to force the shifter beyond the standard position I can feel 5th gear popping on the stick. My question is. Is this a gearset issue or a syncro issue? This is a 420a motor, what 5 speed transmissions are swappable or would it be cheaper just to fix this one if its just a a syncro. It is not a linkage issue I believe as its only that one gear.

Thanks for your help!

 

[ThunderChild]

i havent had a gs trans apart, but you might pop the end case/cap off and check if the fifth gear retainer nut has backed off. this is all depending on if it is similar in build to other 5 spd FWD transmissions out there.

 

[me2151]

how much oil will be in that outer housing? should I drain the whole transmission?

 

[jcastello214]

is drain it and change it while your at it..