Toyota 2.8 Rattle under load

Good morning

I have a 1990 Toyota with the 2.8D motor, it has an after market safari turbo with snorkel fitted.

Recently it has developed a rattle sound which comes in under load, it almost sounds like it is coming from behind the speedo.

There is no sound when it is driven smoothly and not gunned if going up a steep hill, the turbo puts out around 9 psi, I have checked the turbo vanes and there is movement there about a couple of mm side to side, however I have been told this would not make the rattle sound.

Have looked for loose items etc and cannot find any, the motor is well looked after, had a full recon 120,000 ago and has never let me down.

Anyone have any ideas on were to look for the noise, the noise will not come on if the vehicle is revved when stationary, it must be moving and under load at about 3000 revs.

Thanks