sr20det s13 gearbox problems

Hi guys, my box started making some grinding noises in the drive especially in first gear and reverse, but more when im going uphill, so it happens when clutch is completely out and goes gggrrr :facepalm: , i drained the oil and filled up again but still the same happening,
-is it best to get a new box or try fixing this one???
-has anyone experienced it before???
-also can a ca18det fit onto sr20det s13 bellhousing??

The SR bell housing does fits the CA box.

i can organise you a sr box if you want

how much for box , watsapp me 0794953032