Nissan Pickup 1988 Transmission whining

I have a Nissan Pickup 4WD with the 2.4L engine.Question:  Transmission started whining in 1st,2nd, 3rd. 4th gear normal, 5th gear a little whine. Oil change clear with no debris. Trans has 300,000 miles. Is it worth repair or need replace?Answer:   We believer you have the Nissan FS5W71 transmission. Based on you location and the amount of freight we suggest you rebuild or have the unit rebuilt.  We can provide the following parts to fix what we believe to be a bearing wear issue:Bearing Rebuild kit MWT-212WS KIT WITH SYNCRO RINGS your cost $130.00.  This Kit will include all major bearings, gaskets, seals and syncro rings.While your inside the unit you should update the 5th gear set with our parts:Part number NIS-5 5TH GEAR SET your cost $99.00 plus S&H.You can see the other FS5W71 parts we can provide on our web site.