The best replacement for 5.3 is 6.0.

The best alternatives to 5.3 are rated as following:
★★★★★  6.0
★★★★  5.7
★★★★  4.8
★★★  ls1
★★★  6.2
★★★  5.4
★★  350
★  lt1
★  5.0
★  4.8 chevy
★  duramax
★  6.2 vortec
★  hemi
★  6.0 vortec
★  5.7 hemi
★  lq4
  4.8 vortec
  ecoboost
  ford 5.4
  5.7 ls1
  5.2
  6.0 ls
  4.8 engine
  6.0 silverado
  4.8 mpg
  6.0 avalanche
  4.8 silverado
  4.7
  5.7 vortec
  triton 5.4

Your alternative for 5.3 is not listed? Suggest!
Speaking about 5.3, one probably shouldn't forget about 4l80e.

Other search terms related to 5.3 and their ratings are:
★★★★★ 4l80e
★ 700r4
You have in mind a companion for 5.3 and it is not yet here? Propose!



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5.3
6.0
5.7