[Fot] Trunnion/vertical upright

[Greg And Alison Blake]

I am working on a 1970 TR6 and noticed what I think is a worn out trunnion or vertical link. With the car on the lift and application of torque to the trunnion pivot bolt the bolt and trunnion rotate about 10 degrees relative to the vertical link. 

It appears to me that either the trunnion, the vertical link, or both are worn to allow this slop. The trunnion actually looks "new" as compared to the other side of the car which does not have this issue. 

Should the vertical link/trunnion be replaced as a matched set?  Are TR4a-TR6 parts interchangeable (same part numbers at MOSS)

Thanks

Greg