Intermittent sound between shifts

The sound is very intermittent, It usually happens when shifting from 2nd to 3rd gear. It sounds like someone is tapping the floorboard with a hammer after the shift. The vehicle in question is a 2006 Toyota Taco DC Pre Runner 2wd automatic trans.

 

How rapid is this tapping sound?

Does it definitely sound metallic (metal-on-metal)?

 

It sounds like a thud and it only thuds once after the shift from 3-4 or 2-3 but it dosent happen every time.

 

Does it usually happen only when accelerating pretty hard? If it thuds only once, it might be axle wrap or a driveline connection issue.

 

yes it occurs when under a medium to aggressive acceleration.

 

whats axle wrap?

 

'Axle wrap' is when your rear leaf springs deform or twist under load (e.g., causing them to bend into an 'S' shape rather than their usual 'U' shape).

Here's an illustration from DesertRides:




This can cause damaging stresses to the rear and throw things out of alignment (e.g., the pinion angle).

 

is there anything that can be done to prevent it? AAL?