My 92 Chevy Astro shutters when moving. It is most noticable when taking off from a start under load (accleration). I believe it is due to bad u-joints. The van has 167K miles. The rear differential has been replaced within the last year. Any advice?

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles